U.S. Department of the Interior

U.S. Geological Survey

Circular 1286

Marine Mineral Resources of Pacific Islands–A 

Review of the Exclusive Economic Zones of Islands 

of U.S. Affiliation, Excluding the State of Hawaii
Marine Mineral Resources of Pacific Islands—A 

Review of the Exclusive Economic Zones of Islands 

of U.S. Affiliation, Excluding the State of Hawaii

By James R. Hein, Brandie R. McIntyre, and David Z. Piper

Circular 1286

U.S. Department of the Interior

U.S. Geological Survey 
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2005

For sale by U.S. Geological Survey Information Services

Box 25286, Denver Federal Center

Denver, CO 80225-0046

This report and any updates to it are available online at:

http://pubs.usgs.gov/circular/c1286/

For additional information write to:

U.S. Geological Survey

Box 25046, Mail Stop 421, Denver Federal Center

Denver, CO 80225-0046

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Telephone: 1–888–ASK–USGS (1-888-275-8747)

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Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the U.S. Government.

Although this report is in the public domain, it may contain copyrighted materials that are noted in the text. Permission

to reproduce those items must be secured from the individual copyright owners.

Cataloging-in-Publication data are on file with the Library of Congress

Produced in the Western Region, Menlo Park, California

Manuscript approved for publication, September 26, 2005

Text edited by Peter H. Stauffer

Layout and design by Stephen L. Scott 

FRONT COVER

Active sulfide chimneys on the sea bottom at a depth of 345 meters (1,130 feet) in the western Pacific (see p. 5).
Contents

Introduction---------------------------------------------------------------------------------------------------1

Purpose and relevance---------------------------------------------------------------------------------1

Marine mineral deposits: occurrence and formation----------------------------------------------3

Abyssal plains-------------------------------------------------------------------------------------3

Volcanic islands-----------------------------------------------------------------------------------3

Seamounts-----------------------------------------------------------------------------------------5

Atolls ---------------------------------------------------------------------------------------------5

Exclusive Economic Zones----------------------------------------------------------------------------------6

American Samoa---------------------------------------------------------------------------------------------9

Island History--------------------------------------------------------------------------------------------9

Geography-----------------------------------------------------------------------------------------------9

Geologic setting-----------------------------------------------------------------------------------------9

Offshore mineral deposits------------------------------------------------------------------------------9

Summary----------------------------------------------------------------------------------------- 11

Selected References--------------------------------------------------------------------------------- 11

Republic of Belau------------------------------------------------------------------------------------------- 13

Island History------------------------------------------------------------------------------------------ 13

Geography--------------------------------------------------------------------------------------------- 13

Geologic setting--------------------------------------------------------------------------------------- 13

Offshore mineral deposits---------------------------------------------------------------------------- 14

Summary----------------------------------------------------------------------------------------- 15

Selected References--------------------------------------------------------------------------------- 15

Guam------------------------------------------------------------------------------------------------19

Island History------------------------------------------------------------------------------------------ 19

Geography--------------------------------------------------------------------------------------------- 19

Geologic setting--------------------------------------------------------------------------------------- 19

Offshore mineral deposits---------------------------------------------------------------------------- 19

Summary----------------------------------------------------------------------------------------- 20

Selected References--------------------------------------------------------------------------------- 21

Howland and Baker Islands------------------------------------------------------------------------------- 23

Island History------------------------------------------------------------------------------------------ 23

Geography--------------------------------------------------------------------------------------------- 23

Geologic setting--------------------------------------------------------------------------------------- 23

Offshore mineral deposits---------------------------------------------------------------------------- 23

Summary----------------------------------------------------------------------------------------- 24

Selected References--------------------------------------------------------------------------------- 24

Jarvis Island------------------------------------------------------------------------------------------------- 27

III
Island History------------------------------------------------------------------------------------------ 27

Geography--------------------------------------------------------------------------------------------- 27

Geologic setting--------------------------------------------------------------------------------------- 27

Offshore mineral deposits---------------------------------------------------------------------------- 27

Summary----------------------------------------------------------------------------------------- 28

Selected References--------------------------------------------------------------------------------- 28

Johnston Atoll----------------------------------------------------------------------------------------------- 31

Island History------------------------------------------------------------------------------------------ 31

Geography--------------------------------------------------------------------------------------------- 31

Geologic setting--------------------------------------------------------------------------------------- 31

Offshore mineral deposits---------------------------------------------------------------------------- 32

Summary----------------------------------------------------------------------------------------- 33

Selected References--------------------------------------------------------------------------------- 33

Kingman Reef and Palmyra Atoll------------------------------------------------------------------------- 35

Island History------------------------------------------------------------------------------------------ 35

Geography--------------------------------------------------------------------------------------------- 35

Geologic setting--------------------------------------------------------------------------------------- 35

Offshore mineral deposits---------------------------------------------------------------------------- 36

Summary----------------------------------------------------------------------------------------- 37

Selected References--------------------------------------------------------------------------------- 37

Republic of Marshall Islands------------------------------------------------------------------------------ 39

Island History------------------------------------------------------------------------------------------ 39

Geography--------------------------------------------------------------------------------------------- 39

Geologic setting--------------------------------------------------------------------------------------- 39

Offshore mineral deposits---------------------------------------------------------------------------- 40

Summary----------------------------------------------------------------------------------------- 41

Selected References--------------------------------------------------------------------------------- 41

Federated States of Micronesia-------------------------------------------------------------------------- 43

Island History------------------------------------------------------------------------------------------ 43

Geography--------------------------------------------------------------------------------------------- 43

Geologic setting--------------------------------------------------------------------------------------- 43

Offshore mineral deposits---------------------------------------------------------------------------- 44

Summary----------------------------------------------------------------------------------------- 45

Selected References--------------------------------------------------------------------------------- 46

Midway Atoll------------------------------------------------------------------------------------------------ 49

Island History------------------------------------------------------------------------------------------ 49

Geography--------------------------------------------------------------------------------------------- 49

Geologic setting-------------------------------------------------------------------------------------- 49

Offshore mineral deposits---------------------------------------------------------------------------- 49

Summary----------------------------------------------------------------------------------------- 50

Selected References--------------------------------------------------------------------------------- 50

Northern Mariana Islands--------------------------------------------------------------------------------- 53

Island History------------------------------------------------------------------------------------------ 53

IV
Geography--------------------------------------------------------------------------------------------- 53

Geologic setting--------------------------------------------------------------------------------------- 53

Offshore mineral deposits---------------------------------------------------------------------------- 53

Summary----------------------------------------------------------------------------------------- 55

Selected References--------------------------------------------------------------------------------- 55

Wake Atoll--------------------------------------------------------------------------------------------------- 57

Island History------------------------------------------------------------------------------------------ 57

Geography--------------------------------------------------------------------------------------------- 57

Geologic setting--------------------------------------------------------------------------------------- 57

Offshore mineral deposits---------------------------------------------------------------------------- 57

Summary----------------------------------------------------------------------------------------- 58

Selected References--------------------------------------------------------------------------------- 58

Conclusions-------------------------------------------------------------------------------------------------- 60

Acknowledgements---------------------------------------------------------------------------------------- 60

Appendixes

1. Metric system conversion factors--------------------------------------------------------------- 60

2. Definitions and explanation----------------------------------------------------------------------- 60

3. Acronyms and abbreviations---------------------------------------------------------------------- 62

Figures

-- - 1. Index map of the Pacific region, showing unofficial Exclusive Economic Zones-------------2

-- - 2.Schematic diagram of oceanic tectonic and physiographic settings where

-- - - - deep-sea mineral deposits form---------------------------------------------------------------------4

-- - 3.Photograph of iron-manganese nodules on the sea floor in the Johnston Atoll EEZ--------4

-- - 4.Photograph of the cross section of an abyssal iron-manganese nodule----------------------4

-- - 5.Photograph of a group of active sulfide chimneys collected from the Northern

-- - - - Mariana Islands EEZ----------------------------------------------------------------------------------5

-- - 6.Photograph of the cross section of an 18-centimeter-thick iron-manganese

-- - - - crust sample from the Marshall Islands EEZ------------------------------------------------------5

-- - 7. Ocean-floor photograph of iron-manganese crust pavement on Horizon Guyot,

-- - - - Johnston Atoll EEZ------------------------------------------------------------------------------------5

-- - 8.Photograph showing laborers from Belau and Yap working in the phosphate mines

-- - - - on Ngeaur Island, Belau, during World War II-----------------------------------------------------6

9-20.Bathymetric maps of individual EEZs:

-- - 9.American Samoa---------------------------------------------------------------------------------------8

-- 10. Belau (Republic of)---------------------------------------------------------------------------------- 12

-- 11. Guam-------------------------------------------------------------------------------------------------- 18

-- 12. Howland and Baker Islands------------------------------------------------------------------------ 22

V
- - - - -- 13. Jarvis Island------------------------------------------------------------------------------------ 26

- - - - -- 14. Johnston Atoll---------------------------------------------------------------------------------- 30

- - - - -- 15. Kingman Reef and Palmyra Atoll------------------------------------------------------------- 34

- - - - -- 16. Marshall Islands (Republic of)--------------------------------------------------------------- 38

- - - - -- 17. Micronesia (Federated States of)----------------------------------------------------------- 42

- - - - -- 18. Midway Atoll------------------------------------------------------------------------------------ 48

- - - - -- 19. Northern Mariana Islands (Commonwealth of)-------------------------------------------- 52

- - - - -- 20. Wake Atoll-------------------------------------------------------------------------------------- 56

21. Map showing the main potential deep-water mineral deposit type and contained

- - - - metals for each Pacific EEZ of U.S. affiliation--------------------------------------------------- 61

VI


Introduction

Purpose and Relevance

The United States Exclusive Economic Zone (EEZ) was 

established in 1983 and comprises all marine areas within 200 

nautical miles (370 kilometers; see appendix 1 for conversion 

factors) of the nearest U.S. land. This vast area of 3.38 million square nautical miles (11.6 million square kilometers) is 

about 20 percent greater than the entire land area of the United 

States. The resource potential of the vast mineral deposits 

that occur within the U.S. EEZ is unknown, despite field 

studies that have taken place during the past 25 years. Since 

about 1975, information on marine mineral deposits has been 

obtained by numerous research cruises to the Pacific Ocean 

by the U.S. Geological Survey (USGS), the U.S. National 

Oceanic and Atmospheric Administration (NOAA), equivalent 

government agencies in Germany, Canada, France, Russia, 

Japan, China, South Korea, Australia, and New Zealand, and 

by academic researchers from all of these nations. Although 

most of the cruises by other nations explored areas outside the 

U.S. EEZ, information gained from those studies can aid in the 

evaluation of the mineral potential in the U.S. EEZ. However, 

the global effort remains inadequate to allow for the quantitative evaluation of mineral resources contained within the EEZ 

of nations or within international regions of the oceans.

Quantitative information about U.S. EEZ resources is 

essential if governments are to make informed decisions about 

(1) competitive land (sea)-use issues, (2) outer continentalmargin boundary negotiations, (3) environmental-contaminant issues, and (4) energy, mineral, and biologic resources 

potential. The last includes homeland-security concerns such 

as self-sufficiency in energy and strategic and critical mineral 

resources. This report assesses our current state of knowledge 

concerning nonrenewable mineral resources within the EEZ 

of the Pacific islands of U.S. affiliation, exclusive of the State 

of Hawaii. These islands include the U.S. Commonwealth 

of the Northern Mariana Islands; U.S. Territories of Guam, 

Midway Atoll, Wake Atoll, Johnston Atoll, Jarvis Island, Howland-Baker Islands, Kingman-Palmyra Atolls, and American 

Samoa; and the Compact of Freely Associated Nations, which 

comprises three independent nations—the Republic of the 

Marshall Islands, Republic of Belau (Palau), and the Federated 

States of Micronesia (see fig. 1).

A critical concern of coastal nations today is the issue of 

the limits of the outer continental margin and the possibility 

of extending EEZ boundaries on the basis of new geologic 

criteria. A nation’s knowledge of the geology and mineral 

resources in adjacent marine areas is essential in determining 

the placement of EEZ boundaries. Many Pacific island nations 

have few options for generating revenue, and valuable mineral 

resources in the EEZ could offer these nations economic relief.

Many U.S. Government agencies (USGS, Department of 

State, Office of Insular Affairs, Minerals Management Service, 

National Oceanic and Atmospheric Administration) and international agencies (South Pacific Applied Geoscience Commission, International Seabed Authority) regularly receive 

requests from Pacific island nations for information about their 

EEZ resources. However, our ability to provide information on 

resource potential for the U.S. EEZ and those of the Compact 

of Freely Associated Nations is limited by the lack of systematic studies, despite reconnaissance work that has taken place 

during the past several decades. New concerns about homeland security in terms of self-sufficiency in energy and critical 

and strategic minerals now demand that potential contributions from the EEZ be understood and considered in calculations of mineral assessments of the United States. Emerging 

markets for metals in Asia and rapidly developing technologies for fuel-cell and hybrid cars will significantly increase 

global demands for copper, nickel, cobalt, and platinum. 

These are among the most common metals found in deep-sea 

mineral deposits, which will be needed to meet these growing demands. The USGS has a long history of data collection 

and analysis from Pacific islands EEZs. That knowledge base, 

combined with published and unpublished databases, can be 

used to assess our current state of knowledge and ascertain 

what is necessary for quantitative resource assessments. At 

a time when on-land mining faces ever-increasing environmental restrictions and policymakers are confronted with 

increasingly more difficult decisions about land-use priorities, 

it behooves the United States to evaluate the distribution of 

minerals offshore and assess their resource potential.

Marine Mineral Resources of Pacific Islands—A 

Review of the Exclusive Economic Zones of Islands 

of U.S. Affiliation, Excluding the State of Hawaii

By James R. Hein1, Brandie R. McIntyre1, and David Z. Piper1

1

345 Middlefield Road, Menlo Park, CA 94025
 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

0 2,000 km

China

Australia

Hawaii

5

5

5

Indonesia

1

Japan

2

17

18

16 15

14

13

12

11

10

9 8 7

6 4

3

Alaska

New

Zealand

North

America

0O

30ON

30OS

30ON

30OS

120oE 180o 150oE 150oW

A

B

C

D E

F

G

H

I

J

K L

0O

Exclusive Economic Zones (EEZs) in the Pacific Ocean

Island Nations and Territories

Having United States Affiliation

(excluding the State of Hawaii)

A American Samoa (Territory)

B Belau (Republic)

C Guam (Territory)

D Howland and Baker Islands

(Territory)

E Jarvis Island (Territory)

F Johnston Atoll (Territory)

G Kingman Reef and Palmyra Atoll

(Territory)

H Marshall Islands (Republic)

I Micronesia (Federated States )

J Midway Atoll (Territory)

K Northern Mariana Islands

(Commonweatlh)

L Wake Atoll (Territory)

Other Island Nations and Territories

 1 Minomi Tori Shima (Marcus Island)

[Japan]

 2 Papua-New Guinea

 3 Nauru

 4 Solomon Islands

 5 Kiribati (three separate EEZs)

 6 Tuvalu

 7 New Caledonia [France]

 8 Vanuatu

 9 Fiji

10 Wallis and Futuna [France]

11 Tokelau [New Zealand]

12 Samoa

13 Norfolk Island [Australia]

14 Tonga

15 Niue

16 Cook Islands

17 French Polynesia [France]

18 Pitcairn Islands [United Kingdom]

Figure 1. Index map of the Pacific region, showing unofficial Exclusive Economic Zones (200-nautical-mile limits) extending from the shores 

of nations and territories. Those with affiliations to the United States are shaded in purple and are discussed in this circular. Most seamounts 

in the Pacific Ocean are within 200 nautical miles of islands. Consequently, much of the potential seamount resources occur within the EEZs 

shown. (Modified from the Web site of SOPAC, www.sopac.org.fj)


Marine Mineral Deposits: Occurrence and Formation

For each EEZ considered, this compilation presents 

information, when available, for aggregate, sand and gravel, 

precious coral, insular and seamount (submarine volcano) 

phosphorites, cobalt-rich iron-manganese crusts (also known 

as ferromanganese crusts, manganese crusts, or cobalt crusts), 

iron-manganese nodules (also known as ferromanganese 

nodules or manganese nodules), hydrothermal manganese, 

polymetallic sulfides, sulfates, sulfur, epithermal gold and base 

metals, and sedimentary native copper. Data gaps are identified and recommendations made for filling them. For sites 

where no samples have been collected, and therefore no data 

exist, some inferences are made about the minerals likely to 

occur based on our knowledge of their modes of formation and 

the geologic environments in which they are known to occur. 

A brief geologic summary of each EEZ is provided in order to 

understand the minerals that may occur there in a larger context.

To a first approximation, islands and surrounding environments in the Pacific Ocean basin can be divided into four 

geological/oceanographic settings. These settings dictate the 

mineral deposit types possibly hosted within the EEZ of an 

island or island nation. These environments and the main 

mineral deposit types (given in boldface type at first use) that 

occur in each are here described briefly. A schematic representation of these geologic environments is presented in figure 2.

Abyssal Plains

The deep abyssal plains (water depths of 4,000 to 6,500 

meters; 13,100 to 21,300 feet) are relatively flat and sediment 

covered. Iron-manganese nodules commonly form on the 

sea floor where the sediment accumulation rates are low, less 

than 10 centimeters (4 inches) per thousand years (figs. 3, 4). 

Nodule coverage over vast areas of the Pacific Ocean sea floor 

exceeds 50 percent. The nodules are composed mainly of iron 

and manganese oxides, but it is their few weight percent of 

copper (Cu) plus nickel (Ni) and cobalt (Co) that make them 

of economic interest. The primary source of the metals in 

the nodules is ocean water. Nodules form by precipitation of 

metals directly from cold, ambient bottom waters onto the tops 

of nodules and by precipitation from sediment pore fluids onto 

the bottoms of nodules. The metals supplied to the pore fluids 

were initially part of accumulating organic matter or were 

adsorbed on organic and inorganic solids that settled through 

the water column to the ocean floor. The two processes yield 

precipitates of quite different composition. The first type 

(direct precipitation from sea water) results in iron/manganese 

ratios of 0.5 to 1.5 and relatively high cobalt contents, in the 

range of 0.5 percent. The second type (precipitation from pore 

fluids) has lower iron/manganese ratios, commonly in the 

range of 0.2 to 0.5, and relatively high combined Cu and Ni 

concentrations, as much as 3 percent.

This difference in composition is recorded within the nodules and demonstrates quite clearly that the nodules must be 

periodically reoriented on the ocean floor during accretion. An 

unsolved problem is how the nodules can remain at the surface 

and grow large. The nodules accrete metals from seawater at 

a rate that is about 1,000 times slower than the accumulation 

rate of the sediment on which the nodules rest. The reorientation or turning of the nodules apparently keeps them from 

being buried by the more rapidly accumulating sediment. 

Given that the nodules in many areas average several centimeters in diameter and that bottom currents are too weak to 

move the nodules, the mechanism of turning them over is not 

well understood. Turning of the nodules is possibly related to 

the burrowing of fauna that populate the uppermost few centimeters of sediment, including anemones, holothurians, and 

mollusks, among others. This question is not merely academic, 

because maintaining the nodules at the surface is essential for 

their easy recovery during mining.

Volcanic Islands

Three different environments within the Pacific Basin host 

volcanic activity that can lead to the formation of islands:

Spreading ridges. Along these ridges, such as the East 

Pacific Rise, new oceanic crust is created by the outpouring 

of lava along the ridge crest, a process that forms new ocean 

floor continuously on a geologic time scale. The sea floor is 

very young at the spreading-ridge axis and progressively older 

away from the ridge. This creation of new sea floor occurs at 

a rate of a few to a few tens of centimeters per year. This type 

of volcanism rarely forms islands; the best examples are the 

Galapagos Islands in the Pacific and Iceland in the Atlantic. 

Seamounts (submerged volcanoes) are a common product of 

this type of volcanism (see Seamounts below).

Hot spots. Some oceanic volcanoes form above a stationary magma chamber deep within the Earth. Magma rising 

from such a chamber erupts on the sea floor and builds a chain 

of volcanoes as the ocean crust moves over the hot spot as 

the result of sea-floor spreading. The classic example of such 

a chain is the Hawaiian archipelago, in which the Island of 

Hawai’i with its active volcanoes is now positioned over the 

hot spot. In the past, the islands now to the northwest formed 

progressively over the hot spot and then moved away. Thus, 

Maui is older than Hawai’i, and Hawai’i did not exist when 

Maui was over the hot spot; Molokai is older than Maui, Oahu 

older yet, and Kauai still older. This type of volcanism forms 

many islands as well as seamounts.

Deep-sea trenches. The Mariana Trench exemplifies 

these features, where the Pacific Ocean crust is subducted 

(descends) deep into the Earth’s mantle. Subduction creates a 

sea-floor trench and also a chain of volcanic islands (such as 

the Mariana, Yap, and Belau volcanic arcs) above the deeper 

parts of the subduction zone, where part of the subducted 

ocean crust is melted. The magma from that melting rises and 

erupts as lava on the sea floor, eventually building volcanic 

islands. Farther away from the ocean trenches, behind the vol-

 Introduction
 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Hot Spot

Asthenosphere

Lithosphere

Seamounts

Trench

Island Arc

Abyssal Spreading Ridge

Plain

Oceanic Crust

Back-Arc Basin

Spreading Ridge

Figure 2. Schematic diagram of oceanic, tectonic, and physiographic settings where deep-sea mineral deposits form. Hydrothermal 

mineral deposits form along oceanic and back-arc-basin spreading ridges, along island arcs, and at hot-spot volcanoes. Ferromanganese crusts form on the flanks of seamounts and islands, and ferromanganese nodules form on the abyssal sea floor (modified 

from Jose F. Vigil’s illustration in This Dynamic Planet, a wall map published in 1994 jointly by the USGS, Smithsonian Institution, and 

the U.S. Naval Research Laboratory).

canic arc, a type of sea-floor spreading and volcanism called 

back-arc-basin spreading occurs on a smaller scale than at 

oceanic ridges. The volcanism that results from this type of 

sea-floor spreading rarely forms islands, but it is nonetheless 

important to the formation of marine mineral deposits.

Hydrothermal activity is associated with all three of these 

types of volcanism. Polymetallic sulfides, sulfates, and sulfur

may precipitate from the hydrothermal/magmatic fluids associated with the volcanism (fig. 5). Epithermal gold and basemetal deposits form within volcanic arcs, but at deeper levels 

within the volcanic pile. They may be brought to the surface 

by uplift, faulting, and erosion.

Figure 3. A dense concentration of iron-manganese nodules in the 

Johnston Atoll EEZ; field of view is about 4 meters by 3 meters.

Figure 4. Cross section of an abyssal iron-manganese nodule; 

approximate diameter is 1.5 centimeters. Note the concentric, 

wavy growth layers that reflect differences in composition.


Seamounts

Seamounts are submarine volcanoes that may be active 

currently or may have been extinct for millions of years. They 

do not now extend above the ocean surface as islands, but 

some were once islands. However, once the volcanoes that 

built them became dormant, adjustments of the ocean crust 

(weight of the volcanic pile and cooling of the crust) caused 

them to sink as much as 2 kilometers (1.24 miles) by a process 

called isostatic compensation. It has been estimated that about 

50,000 seamounts are present in the Pacific Ocean. As might 

be expected, they occur over a wide range of water depths.

Flat-topped seamounts, known as guyots, were at one 

time islands. Their tops were eroded flat by surface waves as 

the edifices sank following cessation of volcanic construction. 

Conical seamounts were likely never islands, but rather were 

always submerged. Most seamounts in the central Pacific are 

110 to 65 million years old (Cretaceous) and have not been 

volcanically active for tens of millions of years. In contrast, 

seamounts along the East Pacific Rise in the eastern Pacific 

and along volcanic arcs in the western Pacific are young and 

currently support volcanic and hydrothermal activity.

Cobalt-rich iron-manganese crusts and phosphorite

deposits are ubiquitous on old seamounts in the Pacific (fig. 

6). Iron-manganese crusts grow at rates of about 1 to 6 millimeters (0.04 to 0.24 inches) per million years by precipitation 

of metals out of cold ambient bottom waters onto hard-rock 

substrates (fig. 7). Their growth rates are on average about 4 to 

6 times slower than those of copper- and nickel-rich iron-manganese nodules. The crusts form where the seamounts are free 

of sediment. Like nodules, the crusts are composed mainly 

of iron and manganese oxides, but it is their high cobalt contents (0.5 to 2.0 percent) that make them of economic interest. Crusts commonly have high contents of other metals that 

are of economic interest as well, including titanium, cerium, 

nickel, zirconium, platinum, molybdenum, copper, and tellurium.

Atolls

Like seamounts and guyots, atolls are linked to the formation of volcanic islands and their eventual sinking in response 

to adjustments of the oceanic crust. Charles Darwin was 

the first to recognize their origin, and his explanation is still 

Figure 5. A group of active sulfide chimneys from the Northern Mariana Islands EEZ; note the gray particulate matter above and to the 

right of the group of chimneys, which originates from the orifice of 

each individual chimney. Water depth is 345 meters. (http://oceanexplorer.noaa.gov/explorations/04fire/)

Figure 6. A cross-section of an 18-centimeter-thick iron-manganese 

crust sample from the Marshall Islands EEZ; collected from 1,780-

meter water depth.

Figure 7. Ocean-floor photograph of iron-manganese crust pavement 

on Horizon Guyot, Johnston Atoll EEZ; image covers about 3 meters by 

4 meters of sea floor at 2,000-meter water depth.

 Introduction
 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

accepted today. Low-latitude (0-30°) volcanic islands develop 

barrier reefs, an important structural element of which is 

calcium carbonate secreted by corals and algae. A vast community of other organisms and their remains also contribute to 

the building and maintenance of the reefs. As volcanic islands 

sink, fringing reefs grow upward and become barrier reefs 

with shallow lagoons between the reefs and the islands. With 

the continued subsidence of the island below sea level and 

continued upward growth of the reef, formation of the atoll is 

complete. The exposed reef becomes more or less continuous, 

encircling an inner lagoon, and there may be no visual evidence of the totally submerged underlying volcanic edifice.

Some ancient atolls have been uplifted by movement of 

the oceanic crust over swells in the Earth’s mantle (called 

lithospheric swells). These former atolls have been transformed into carbonate platform islands with as much as 90 

meters of elevation. Perhaps the best known is the island of 

Nauru, in the western part of the equatorial Pacific Ocean, 

but many others exist.Several atolls and carbonate platform 

islands had significant deposits of lagoonal or insular phosphates, most of which were mined in the early part of the 

20th century (fig. 8). On Nauru, site of by far the largest such 

deposit, mining continued throughout the 20th century. The 

source of this phosphate was bird guano. The vast avian 

colony required for the formation of the deposit occupied the 

island from the time when it was still an atoll until it became 

totally emergent, and possibly for some time thereafter. The 

phosphate deposit on the Chincha Islands along the coast of 

Peru demonstrates the existence of such prodigious guano 

sources. There, the compacted and altered guano phosphate 

deposit was approximately 45 meters thick. As fresh guano, 

accumulating at a rate of several meters per 100 years, the 

Chincha deposit would have been in excess of 400 m thick. 

The deposits on Nauru required approximately this same 

remarkable amount of fresh guano.

Understanding these different environments makes it 

possible to predict the mineral-deposit types that are likely to 

occur within a given EEZ, even if no samples have been collected. However, without detailed sampling and mapping of an 

area, it is not possible to make a quantitative mineral resource 

assessment.

Exclusive Economic Zones

Information for each of the 12 island territories considered here is organized into two parts: The first part is introductory material consisting of land area, EEZ area, political status, 

Figure 8. Laborers from Belau and Yap working in the phosphate mines on Ngeaur Island, Belau during World War II. George Fritz Collection, 

MARC, cited in Pacific Worlds Yap-Ulithi Web site: “Getting There” Pacific Worlds, 2003, http://www.pacificworlds.com/yap/visitors/colony.cfm


population estimates for either 2003 or 2004 (as available), 

minerals that occur on the islands, island history, geography, 

and geologic setting. The second part is an assessment of our 

state of knowledge concerning the offshore mineral deposit 

types found, or likely to be found, within each EEZ. This 

second part concludes with an EEZ mineral summary and a 

list of selected reference materials. An EEZ map accompanies 

each section. 

Definitions and explanations of the main terms used 

are presented in appendix 2, and acronyms are explained in 

appendix 3. All chemical concentrations in the text are listed 

as weight percents. The geologic time scale used here is that 

of the International Commission of Stratigraphy (Gradstein, 

F.M., Ogg, J.G., Smith, A.G., Bleeker, W., and Lourens, L.J., 

2004, A new geologic time scale with special reference to 

Precambrian and Neogene: Episodes, v. 27, no. 2, p. 83-

100).

Generally we refer to near-term resource potential to 

mean within the next 25 years, intermediate-term is 25-50 

years, and long-term is more than 50 years. Actual exploitation of resources will depend on other factors. Even though 

iron-manganese crusts, for example, is listed to have an intermediate-term resource potential for several EEZs, the global 

market would likely not support mining from more than one or 

two of those EEZs. Five to ten seamounts could support a 20-

year mining operation for crusts, which would supply about 

15 percent of the annual global need for cobalt. Competing 

mining operations would probably not be economic for cobalt, 

although nickel, platinum, and other rare metals might support 

additional operations if warranted by the global markets for 

those metals. Technology also plays an important role in the 

exploitation of deep-sea minerals. For example, the advantage 

of the exploitation of iron-manganese nodules versus ironmanganese crusts is their relative ease of recovery, whereas 

the advantage of mining crusts is their occurrence at shallower 

water depths and their higher contents of rare metals. Several 

types of phosphorite deposits occur within most of the EEZs 

considered here. Many phosphorite mines on land will be 

depleted soon and new sources need to be found. Phosphorite is used in agriculture as a fertilizer and in the food and 

beverage industries to make the ingredient phosphoric acid. 

Phosphorite is the commodity that made the island nation of 

Nauru at one time rich and famous. These and other changing economic, political, security, technological, and land-use 

issues could significantly affect the realization of the resource 

potential estimates for the commodities considered here.

 Exclusive Economic Zones
 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Figure 9. Bathymetric map of the Exclusive Economic Zone (EEZ) of American Samoa (“A” on fig.1); black line shows EEZ boundary. Contour

interval is 500 meters. The Tokelau, Cook Islands, Niue/Tonga, and Samoa EEZs border the American Samoa EEZ to the north, east, south, and 

west, respectively.

Fe-Mn crust sample sites

Fe-Mn nodule sample sites

 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

Swains Island

MANIHIKI

 PLATEAU

Tokelau Islands

ROBBIE RIDGE

 SAMOA

 BASIN

SAMOA RIDGE

Manu'a Islands

 (Ta'u, Ofu, Olosega)

Tutuila Island

Savai'i Island

Upolu

Island

Rose Island

TONGA

TR

E

N

CH

175oW 170oW 165oW

15oS

10oS

Pukapuka

Island

Vava'u Islands

Group

DEPTH, IN METERS

Vailulu'u

15oS Seamount

10oS

175oW 170oW 165oW

Aunu'u I.


American Samoa

Land area: 198 km2 (5 volcanic islands: Tutuila, 

 ‘Aunu’u, Ofu, Olosega, Ta’u; 2 

 coral islands: Rose, Swains)

EEZ area: 390,000 km2 (see fig. 9); location 

 shown by “A” on figure 1

Political 

status: An unincorporated and unorganized 

 territory of the United States

Population: 70,260 (July 2003 estimate)

Island minerals: Pumice (pumicite), pozzolan

Island History

American Samoa was settled circa 600 B.C., perhaps by 

migrants from the west by way of Indonesia, Vanuatu, Fiji, 

and Tonga (fig. 1). European explorers first visited the islands 

in the 18th century, the initial visit being by the Dutch explorer 

Jacob Roggeveen in 1722. Claim disputes among Germany, 

the United Kingdom, and the United States were settled by 

the 1899 Treaty of Berlin, in which the United States received 

the smaller group of eastern islands (Tutuila and Aunu’u), 

which it formally occupied the next year. The deed of cession was signed on 17 April 1900, and the U.S. Navy took 

over administrative duties. Ta’u, Ofu, Olosega (the Manu’a 

Islands), and Rose Island were ceded to the United States in 

1904. Swains Island became part of American Samoa in 1925 

by a joint resolution of Congress. In 1951, President Truman 

transferred administration of the islands to the Department of 

the Interior.

Geography

American Samoa is the southernmost U.S. territory, centered at about 14°S latitude. It is located 3,700 kilometers 

southwest of Hawai’i and 2,574 kilometers northeast of New 

Zealand. Tutuila Island possesses an excellent natural deepwater harbor at Pago Pago, which rests at the base of Mt. 

Matafao, the second highest peak in the territory at 653 m. The 

highest peak is Lata Mountain at 966 m on Ta’u Island. Ofu, 

Olosega, and Ta’u Islands form the Manu’a Islands group (see 

fig. 9). Swains Island is an atoll without a channel connecting 

the central lagoon and the open ocean, whereas Rose Island is 

a typical atoll with free exchange of water between the lagoon 

and open ocean.

Geologic Setting

The EEZ of American Samoa encompasses a variety of 

geologic, morphologic, and tectonic environments (see fig. 

9). The sediment-covered, deep-water Samoa Basin occupies 

most of the eastern half of the EEZ. Seamounts of unknown 

age penetrate through the sediment in the Samoa Basin, mostly 

near the southern and northern margins of the EEZ. A small 

piece of the Manihiki Plateau, a feature about 110 million years 

old, occupies the northeast corner of the EEZ and includes 

several seamounts. The eastern end of Samoa Ridge occupies 

the west-central part of the EEZ. This ridge is composed of the 

geologically young (1.5 million years old to recent) volcanoes 

that form all the islands within the American Samoa EEZ, 

except Swains Island. Tutuila Island has a maximum age of 

about 1.5 million years, and Ta’u Island has had recent volcanic 

activity. The hot spot (stationary magma chamber deep in the 

Earth) that created the entire Samoa island chain and ridge (in 

both Samoa and American Samoa) lies about 45 kilometers 

east of Ta’u Island (part of the Manu’a Islands) and its active 

sea-floor manifestation is called Vailulu’u seamount (fig. 9). 

This seamount is both volcanically and hydrothermally active. 

Part of Robbie Ridge occupies the northwest corner of the EEZ 

and includes Swains Island and several seamounts. The age of 

Robbie Ridge may be similar to that of Manihiki Plateau. The 

southwest margin of the EEZ is sediment covered and abuts the 

outer (eastward) margin of the Tonga Trench. 

Offshore Mineral Deposits of American Samoa

The Exclusive Economic Zone (EEZ) of American Samoa 

contain potential mineral resources that likely include:

• Cobalt-rich iron-manganese crusts on seamounts in the 

Samoa Basin and on Robbie Ridge and Manihiki Plateau

• Iron-manganese nodules in the deep Samoa Basin

• Phosphorite deposits on seamounts and the flanks of 

islands

• Insular and lagoonal phosphorite on Rose and Swains 

Islands

• Native copper deposits on Manihiki Plateau

• Hydrothermal manganese oxide, iron hydroxide, and 

sulfide deposits on Samoa Ridge

• Shallow-water sand, gravel, and aggregate deposits near 

the islands

• Shallow- to deep-water precious coral adjacent to the 

islands and on seamounts

Cobalt-rich iron-manganese crusts likely occur on the 

several large and many small seamounts located in the Samoa 

Basin, Manihiki Plateau, and Robbie Ridge. However, the 

distribution and morphology of the seamounts in the EEZ 

are poorly known, and the grade and tonnage of the metalrich crusts that may occur on those seamounts are unknown, 

because no research cruises have been dedicated to their 

study. Analyses of only two samples of cobalt-rich crusts collected within the EEZ are available (see fig. 9). Neither of 

those samples is from a location likely to contain the highest 

potential cobalt-crust resource. The two analyses indicate low 

contents of total copper plus nickel plus cobalt (1.0 and 0.6 

 American Samoa
10 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

percent). However, the most economically important of those 

three metals is cobalt, and it is quite high in one of the samples 

(0.7 percent).

A crust sample collected about 90 kilometers (50 nautical 

miles) north of the American Samoa EEZ boundary (see fig. 

9) was analyzed recently by the USGS and has a similar content of the three metals (total of 1.1 percent). However, this 

sample has moderately high contents of cobalt and rare metals 

(tellurium, titanium, tungsten, zirconium) and is relatively 

thick (45 millimeters; the cut-off thickness for crust mining 

is estimated to be about 25 to 40 millimeters). A crust sample 

collected just north of Pukapuka Island in the Cook Islands 

EEZ (see fig. 9) has a very high combined cobalt/nickel/

copper content of 2.67 percent, with cobalt being dominant 

at 1.84 percent. These two crusts are likely to be similar in 

composition to those on seamounts in the northern part of 

the American Samoa EEZ. Iron-manganese crust deposits 

may have an intermediate-term resource potential for cobalt 

and possibly nickel, platinum, and other rare metals. These 

deposits within the American Samoa EEZ need to be mapped 

and characterized before their place in the global inventory of 

crusts can be evaluated.

Iron-manganese nodules likely occur on the sediment 

surface of the Samoa Basin, where sediment accumulation 

rates are less than 5 millimeters per 1000 years. However, the 

distribution, grade, and tonnage of the nodules are not known. 

Of the 12 sediment samples collected in the American Samoa 

part of the Samoa Basin, 6 contained nodules along with the 

sediment (fig. 9). The abundances of nodules in those samples 

were estimated as low to medium. Nine nodule samples were 

analyzed from the Samoa Basin, but it was not specified how 

many of those were from the American Samoa EEZ and how 

many from the Cook Islands EEZ. The copper plus nickel and 

cobalt contents are low (with a mean of 0.7 percent and a maximum of 1.1 percent). These values may be typical for nodules 

in the American Samoa EEZ; however, a survey should be 

done because nodules in the Penrhyn Basin on the east side of 

the Manihiki Plateau (Cook Islands EEZ) have been studied in 

detail and found to be enriched in cobalt. As a result, that area 

is considered a potential mining target.

The Samoa Basin area adjacent to Samoa Ridge has rapid 

sediment accumulation rates because of material shed from 

the ridge; that area will not be prospective, because those 

sedimentation rates inhibit the growth of nodules. If areas of 

favorable nodule density and grades can be located, then those 

nodules would offer an intermediate-term potential resource.

Seamount phosphorite commonly occurs on seamounts 

along with iron-manganese crusts. The distribution and grade 

of such deposits in the American Samoa EEZ are unknown. 

These deposits are typically either small, high-grade deposits 

or widespread, low-grade deposits. This deep-water deposit 

type may have a long-term resource potential.

Insular phosphorite may occur on Rose and Swains 

Islands. A drilling program on the islands and in their lagoons 

would be required to delineate a potential resource. If significant deposits are found, they could offer an immediate 

potential resource. However, Rose Island is a U.S. National 

Wildlife Refuge, and exploration and exploitation there are 

prohibited.

Native Copper has been recovered from several places 

on Manihiki Plateau and may occur in the American Samoa 

EEZ, although that part of the plateau has not been sampled. If 

native copper does occur in the EEZ, it would probably have a 

long-term resource potential.

Hydrothermal oxide and sulfide deposits may be 

found associated with fracture zones and seamounts along the 

Samoa Ridge, especially where volcanic activity has occurred 

recently (for example, off Ta’u Island in the Manu’a Island 

group). The Samoa Ridge has not been explored for such 

deposits, but the hydrothermal activity that produces them 

exists in the summit crater of Vailulu’u seamount (fig. 9). That 

crater should be an important target for exploration. If the 

deposits are similar to others from volcanically active areas in 

the Pacific, then hydrothermal manganese and iron oxides will 

be found to cement volcanogenic sand layers and form stratabound layers within the sediments and rocks.

The manganese deposits may have high contents of 

nickel, molybdenum, and chromium. However, large deposits 

of manganese, iron, molybdenum, and chromium occur on 

the continents, giving these metals only a long-term resource 

potential if found in the EEZ; large nickel-rich deposits could 

offer an intermediate-term resource potential. On the other 

hand, sulfide deposits may have high contents of gold and 

silver, as well as copper, lead, and zinc. Sulfide deposits may 

form at and/or below the sea floor, depending on the conditions of the hydrothermal system. If gold- and silver-rich sulfides are found within the American Samoa EEZ, they could 

offer a near-term resource potential.

Sand and gravel deposits occur in shallow water adjacent 

to most of the coastline of Tutuila and the Manu’a Islands 

and is the only potential mineral resource within the EEZ that 

has been the subject of some exploration. Large tonnage and 

exploitable deposits occur in Nua-Seetaga Bay and Fagaitua 

Bay on Tutuila Island. Additional exploitable deposits may 

also occur on Taema and Nafanua Banks. Smaller offshore 

sand and gravel deposits and beach sands occur in many 

other places adjacent to these islands. However, exploitation 

of the smaller deposits and the beach sands would have to 

consider environmental issues. Exploitation of numerous onland limestone and volcanic-rock outcrops found in relatively 

remote areas can provide building aggregate as an alternative 

to offshore mining. Fluvial aggregate and beach sand deposits 

are very limited in American Samoa. Nua-Seetaga Bay and 

Fagaitua Bay offer a near-term resource potential for aggregate and could be mined now if environmental issues can be 

satisfactorily addressed.

Precious coral is found in shallow to deep water at many 

places along the Samoa Ridge. A systematic exploration 

program is needed to determine whether a potential resource 

exists. Precious coral should also occur on seamounts located 

throughout the EEZ. Precious coral has an immediate market 

if a suitable deposit can be located, but caution must be used 
11

to prevent depletion of the resource beyond the point at which 

it can be renewed and to ensure that collection methods are 

selective.

Summary

The American Samoa EEZ is essentially unexplored for 

cobalt-rich crusts, nodules, phosphorites, hydrothermal deposits, and precious coral. Although resource evaluations are not 

possible, environments are present that offer targets for likely 

mineral occurrences. Sand and gravel, precious coral, insular phosphorite, and gold-rich sulfides may have a near-term 

resource potential if suitable deposits are located; cobalt-rich 

crusts, nodules, and copper-lead-zinc sulfides, an intermediateterm resource potential; and seamount phosphorites and native 

copper deposits, a long-term resource potential. Research 

cruises dedicated to mineral-deposit studies are required to 

locate deposits, map their distribution, determine grades and 

tonnages, and develop criteria to aid in further exploration. 

In addition, bathymetric maps of the American Samoa EEZ 

are not adequate for exploration. Parts of the EEZ should be 

mapped using multi-beam and side-scan sonar techniques.

Selected References

Cullen, D.J., 1996, Ferromanganese crusts on seamounts in 

the North Fiji Plateau-Samoa Basin region, in Meylan, 

M.A., and Glasby, G., eds., Manihiki Plateau, Machias and 

Capricorn Seamounts, Niue, and Tofua Trough; Results of 

Tui Cruises: SOPAC Technical Bulletin 10, p. 109-117.

Dingler, J.R., Wolf, S.C., and Carlson, D., 1986, Offshore sand 

resources along the south shore of Tutuila Island, American 

Samoa U.S. Geological Survey Open File Report 86-112, 

43 p.

Dingler, J.R., Carlson, D.V., and Sallenger, A.J., Jr., 1987, 

Map showing locations and statistical parameters of beach 

and offshore sand samples, Tutuila Island, American Samoa: 

U.S. Geological Survey Miscellaneous Field Studies Map 

1875, scale 1:48,000.

Exon, N.F., 1981, Manganese nodules in the Cook Islands 

Region, Southwest Pacific: South Pacific Marine Geological 

Notes, CCOP/SOPAC, v. 2, no. 4, p. 47-65.

Exon, N.F., 1982, Offshore sediments, phosphorite and 

manganese nodules in the Samoan Region, southwest 

Pacific: South Pacific Marine Geological Notes, CCOP/

SOPAC, v. 2, no. 7, p. 103-120.

Hart, S.R., Staudigel, H., Koppers, A.A.P., Blusztajn, J., 

Baker, E.T., Workman, R., Jackson, M., Hauri, E., Kurz, 

M., Sims, K., Fornari, D., Saal, A., and Lyons, S., 2000, 

Vailulu’u undersea volcano; the new Samoa: Geochemistry, 

Geophysics, Geosystems, v. 1, no. 2000GC000108, 13 p.

Hein, J.R., Koschinsky, A., Halbach, P., Manheim, F.T., Bau, 

M., Kang, J.-K., and Lubick, N., 1997, Iron and manganese 

oxide mineralization in the Pacific, in Nicholson, K., 

Hein, J.R., Bühn, B., and Dasgupta, S., eds., Manganese 

mineralization; geochemistry and mineralogy of terrestrial 

and marine deposits: London, Geological Society of London 

Special Publication 119, p. 123-138.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Palfreyman, W.D., Doutch, H.F., Brathwaite, R.L., 

Masaharu, K., Piper, D.Z., Swint-Iki, T.R., McCoy, F.W., 

Sullivan, L.G., Manheim, F.T., and Lane-Bostwick, C.M., 

1996, Mineral-resources map of circum-Pacific region, 

southwest quadrant: U.S. Geological Survey CircumPacific Map Series, 1 sheet, scale 1:10,000,000, with 

booklet, 66 p.

Piper, D.Z., McCoy, F.W., and Swint, T.R., 1985, Manganese 

nodules, sea floor sediment, and sedimentation rates for 

the circum-Pacific region: Tulsa, Oklahoma, American 

Association of Petroleum Geologists, 1 sheet, scale 

1:17,000,000.

Usui, A., Nishimura, A., and Mita, N., 1993, Composition and 

growth history of surficial and buried manganese nodules in 

the Penrhyn Basin, Southwestern Pacific: Marine Geology, 

v. 114, p. 133-153.

 American Samoa
12 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Figure 10. Bathymetric map of the Exclusive Economic Zone (EEZ) of Belau (“B” on fig.1); black line shows EEZ boundary. Contour interval is 

500 meters. The Federated States of Micronesia and Indonesia EEZs border the Belau EEZ to the east and south, respectively.

9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

10,000

130o E

130oE

135o E

135o E

140o E

140o E

5o N 5o N

10o N 10o N

Fe-Mn crust sample sites

WEST

 CAROLINE 

 BASIN

PHILLIPINE

 BASIN

PARECE 

 VELA

 BASIN

Yap Island CAROLINE RIDGE

SOROL RIDGE

Ngeaur Island

Oreor Island

Beliliou Island

Babeldaob Island

PALAU-KYUSHU RIDGE

BELAU TRENCH

YAP

TRENCH

TRENCH

MARIANA

Hydrothermal Mn sample site Sample sites with both Fe-Mn crusts and hydrothermal Mn

Ulithi

Island
13

Republic of Belau (Formerly Palau)

Land area: 495 km2 (~300 islands)

EEZ area: 629,000 km2 (see fig. 10); location 

 shown by “B” on figure 1

Political status: Independent nation in free associa- 

 tion with the United States

Population: 19,626 (2003 estimate)

Island minerals: Aggregate, bauxite, gold, insular 

 phosphate, lignite, kaolinite

Note: The Belauan spellings are used for island names throughout this section.

Island History

Like the rest of Micronesia, Belau was first occupied 

between 1,000 and 2,000 B.C. by immigrants from the southwest Pacific—Indonesia, Melanesia, and perhaps Polynesia. 

The first western contact was a rather inauspicious occasion 

in l783, when the explorer Captain Henry Wilson of England, 

aboard the vessel Antelope, ran aground on one of the rock 

islands located between Oreor (formerly Koror) and Beliliou 

(formerly Peleliu) Islands. The crew spent several months on 

the islands rebuilding the ship. The British dominated trade 

with Belau until 1885, at which time Spain took control of 

the islands. Spain maintained control until 1899, at which 

time Belau and the rest of the Caroline and Northern Mariana Islands were sold to Germany, following the defeat of 

Spain in the Spanish-American War. Germany administered 

the islands from 1899 to 1914 and developed their natural 

resources by conscripting native laborers. These laborers 

mined phosphate on Ngeaur Island (formerly Angaur) and 

developed coconut plantations.

Japanese forces occupied Belau in 1914 by a mandate 

from the League of Nations, which recognized the Emperor 

of Japan as the authority in Micronesia. The Japanese 

increased development of mining, agriculture, and commercial fishing. They changed the economy from one of 

subsistence to a market economy. The population swelled to 

over 40,000, with less than 25 percent being Belauans. Belau 

became a closed military region in 1938, and campaigns 

during WWII took place throughout the islands, with major 

battles on Beliliou, Ngeaur, and Oreor.

The United Nations (U.N.) created the Trust Territory 

of the Pacific Islands (TTPI) in 1947 and named the United 

States the administrative authority. Belau was the last TTPI 

district to reach independence. In the late 1970s, the United 

States installed a considerable capital improvement program 

(CIP) with the goal of building major infrastructure projects 

(airport, dock, roads, and water, power, and sewer systems) 

in each of the TTPI district centers. Independence from the 

U.S.-administered U.N. Trusteeship and initiation of the 

Compact of Free Association with the United States were 

entered into on 1 October 1994. U.S. and Belau officials had 

initially signed the compact eight years before that date, on 10 

January 1986. It was officially enacted on 14 November 1986. 

Belau became the 185th member of the U.N. on 15 December 

1994.

Geography

There are about 300 islands in Belau, and nine of them 

are permanently inhabited. The archipelago extends for about 

240 kilometers, but the length of the Belau volcanic arc is 

about 350 kilometers. The Belau Islands represent the exposed 

summit of an arcuate submarine ridge, the Belau Ridge (Belau 

volcanic arc), which is the southernmost arc in a series of arctrench systems that include the Yap, Mariana, and Izu-Bonin 

systems to the north. The largest island is Babeldaob (Babelthuap), most of which has been inaccessible until recently. A 

ring road is presently being built around Babeldaob.

The Belau group of islands is encircled by a part-barrier part-fringing reef, except for the northernmost islands, 

Ngcheangel (formerly Kayangel), and the southernmost 

island, Ngeaur. The Ngcheangel Islands constitute an atoll, 

and Ngeaur Island is an uplifted coral platform with a maximum elevation of 56 m. The atoll surrounded by the barrier 

reef extends south and west of Babeldaob Island. It encloses 

many smaller islands, which themselves have fringing reefs. 

The highest elevation in Belau, 287 meters above sea level, is 

on Babeldaob.

Geologic Setting

The Belau volcanic arc, of which the Belau Islands are 

the subaerial expression, began formation just under 40 million years ago. It remained volcanically active until about 20 

million years ago, at which time subduction of the Pacific 

Plate under the Philippine Plate ceased in that region, though 

it continued further northeast along the Yap and Mariana 

arcs. It is likely that subduction is currently occurring only 

at a very slow rate along the Yap Trench, but it is very active 

along the Mariana Trench. The Belau Arc is now part of the 

Palau-Kyushu Ridge, which is an extinct volcanic arc (remnant arc), located for the most part in the Philippine Sea backarc basin.

The southeastern part of the Belau EEZ consists of the 

sediment-covered West Caroline Basin. That basin is part 

of the West Caroline microplate, which formed by sea-floor 

spreading about 35 million years ago. The northeastern part 

of the EEZ includes the westernmost extent of the Yap Trench 

and Arc and the southwesternmost part of the Parece Vela 

Basin, part of the Yap-Mariana back-arc basin. The Parece 

Vela Basin crust began formation about 40 million years ago. 

The central part of the Belau EEZ is occupied by the Belau 

arc-trench system and the northern extension of the arc into 

the Palau-Kyushu Ridge, where volcanism ended about 25 

million years ago. The western third of the EEZ consists of 

 Republic of Belau (Formerly Palau)
14 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

the sediment-covered West Philippine Basin, which began 

to form by sea-floor spreading about 60 million years ago. 

Numerous seamounts penetrate through the sediment in that 

basin.

The oldest rocks exposed on the Belau Islands are of 

volcanic origin and are related to subduction and arc formation. Those rocks are overlain in places by carbonate reef 

limestones of Pliocene through Holocene ages (less than 5 

million years old). Similar rocks largely make up the uplifted 

carbonate platform islands of Beliliou and Ngeaur. Bauxite 

(aluminum ore) was mined on Babeldaob Island from two 

(Ngardmau, Ngeremlengui) of the dozens of prospects identified there. Mining ceased during World War II after a total of 

369,227 metric tones, averaging 52 percent aluminum oxide 

(Al2O3), was produced between 1938 and 1944. About 2 million tonnes of proved reserves of 30 percent Al2

O3 still exists, 

as well as much more lower grade ore. Phosphate was mined 

in Belau and is discussed below. At the Rois Malk epithermal 

gold deposit on southeast Babeldaob Island, volcanic rocks are 

overlain in fault contact by a sequence of poorly consolidated 

shale, shaly siltstone, and pebble conglomerate. Locally, these 

rocks are highly enriched in organic matter, constituting lignite 

(coal) deposits. The lignite was briefly mined during World 

War II along with interbedded layers of kaolinite (white clay) 

that was used for ceramics.

Offshore Mineral Deposits of Belau

Despite the occurrence of onshore phosphorite on Ngeaur 

and gold deposits on Babeldaob, cobalt-rich iron-manganese 

crusts, seamount phosphorites, and other possible offshore 

deposits have been little sampled and studied. The Belau EEZ 

shares its northeastern boundary with the Federated States of 

Micronesia, its southern boundary with Indonesia, and part of 

the western boundary with the Philippines. Mineral deposits 

that do, or should, occur within the EEZ include:

• Cobalt-rich iron-manganese crusts associated with 

seamounts and ridges

• Phosphorite deposits on seamounts and ridges

• Insular and lagoonal phosphorite on Ngeaur, Beliliou, 

Mecherchar, and other islands

• Hydrothermal iron and manganese deposits on seamounts 

and ridges

• Epithermal gold along the Belau Arc

• Shallow-water sand and gravel (aggregate) around islands

• Shallow- to deep-water precious coral on seamounts, 

ridges, and islands slopes

Cobalt-rich iron-manganese crusts have been relatively 

extensively studied along the Palau-Kyushu Ridge, but only 

sparingly elsewhere within the Belau EEZ. The Palau-Kyushu 

Ridge contains widespread crust deposits with relatively low 

contents of cobalt, nickel, and platinum and moderate amounts 

of copper. Three crust samples from the Belau EEZ yielded 

average cobalt, copper, and nickel contents of 0.29 percent, 

0.11 percent, and 0.28 percent, respectively. On West Caroline 

Basin seamounts, crusts tend to be thin, averaging about 10 

millimeters and having a maximum thickness of about 40 millimeters. The many seamounts in the southern third of the EEZ 

have not been sampled. The potential for crust resources in the 

Belau EEZ is probably low, but data are few, warranting an 

exploration survey. Iron-manganese nodules are not known to 

occur in the Belau EEZ. Their paucity there can be attributed 

to high sediment accumulation rates on the abyssal sea floor.

Phosphorite deposits are widespread on seamounts and 

ridges throughout the Palau-Kyushu Ridge and seamounts in 

the West Caroline Basin. They occur in the same places as the 

iron-manganese crusts. The deposits are high grade and cover 

large areas, but individual deposits are generally small. Additional exploration is warranted, even though this deposit type 

is likely to have only a long-term resource potential.

Insular phosphorite was mined on Ngeaur, Beliliou, and 

Mecherchar (Eil Malk) Islands, and many prospects occur on 

those islands and also on Ngeruktabel (Urukthapel), Tobi, Pulo 

Anna, and Sonsorol. Phosphate was discovered on Ngeaur and 

Beliliou in 1903. Exploitation started during German occupation in 1909 on Ngeaur and during Japanese occupation in 

1935 on Beliliou. Between 1909 and 1951, about 3,200,000 

metric tonnes of phosphate was mined on Ngeaur. Mining 

decreased after 1951 and was suspended in 1955. Reserves on 

Ngeaur are estimated to be about 500,000 to 700,000 tonnes 

of 37 percent P2

O5. Reserves on Mecherchar are estimated at 

300,000 to 500,000 tonnes containing ≥25 percent P2

O5; about 

4,000 tonnes was previously mined on that island. Reserves on 

Beliliou are estimated at 155,000 tonnes of 32 percent P2O5; 

145,800 metric tonnes was previously mined there. Additional 

estimated reserves are present on Tobi (120,000 tonnes of 30 

percent P2

O5), Pulo Anna (5,000 tonnes of 29 percent P2O5), 

and Sonsorol (20,000 tonnes of 30 percent P2O5).

The deposits mined in the early to middle 1900s were 

high grade. Production reached a maximum in the late 1930s, 

when slightly more than 142,200 metric tonnes was shipped 

to Japan annually. The potential for additional insular and 

lagoonal phosphorites is unknown, but is likely to be small. 

Still, a drilling program in the southernmost region of the 

lagoon in the vicinity of Beliliou Island might identify additional resources.

Epithermal gold deposits hosted in quartz veins occur in a 

small area of southeast Babeldaob Island, at Rois Malk. Gold 

concentrations are as high as 15 grams per ton, but average 

less than 1 gram per ton. One dredge haul seaward of Babeldaob Island collected vein quartz-epidote rocks with very small 

enrichments of gold. Still, the recovery of such vein quartz 

warrants a greater investigation. Location of deposits of sufficient tonnage and grade would have a short-term resource 

potential.

Hydrothermal iron and manganese deposits have been 

identified on Babeldaob Island. They likely also occur on 

submerged banks and slopes scattered throughout the region. 

A research program will be required to evaluate their resource 
15

potential, but they are likely to have only a long-term resource 

potential.

Shallow-water sand and gravel that can be used for construction aggregate consists of coral and shell. Past construction on the islands has used hard-packed coral gravel, cement, 

and volcanic rock aggregate. Locating lagoonal and nearshore 

sand and gravel deposits might have immediate economic 

importance for local construction. However, outcrops of volcanic rock on Babeldaob and Oreor Islands offer a better alternative to mining aggregate offshore.

Shallow- to deep-water precious corals occur in the 

lagoons and on island slopes, seamounts, and ridges in the 

Belau EEZ. Small operations have mined black and red coral 

in Belau for local use. A survey for black coral (Antipathes 

dichotoma) between Babeldaob and Beliliou Islands found 

many occurrences, both inside and outside the barrier reef. 

Samples outside the reef are larger, have more branches, and 

cover a larger depth range, but those inside the reef are easier 

to collect. It has been estimated that the maximum sustained 

yield of black coral is about 635 kilograms per year. Fern 

black coral (Antipathes ulex) has also been found in Belau 

waters and when polished reveals streaks of gold that give it 

the appearance of gold corals found in Hawai’i. Fern black 

coral is rather rare and therefore has little resource potential.

High quality Corallium clatius, precious pink coral, has 

been found at a number of locations between Beliliou and 

Ngeaur Islands. However, very little is known about its distribution. Melitodidae (M. albitincta and M. Mopsella sp.) red 

coral has also been found in Belau waters. This type of coral 

is less valuable than pink coral because it has a duller luster 

and is softer. Nonetheless, it has been collected in Belau and 

used locally in making jewelry and for ornamental displays. 

Bamboo coral has been collected in deep water in many 

dredge hauls that sampled Fe-Mn crusts and phosphorite 

throughout this region of the Pacific. However, its distribution, 

abundance, and resource potential are unknown.

Belau appears to have numerous potential sites for the 

harvesting of precious coral. A systematic exploration program 

is needed to delineate this valuable resource. If important 

deposits can be located, they would have an immediate economic market. It is, however, essential to harvest the coral 

at a rate that would not deplete the stocks and with adequate 

resource conservation measures.

Summary

In the Belau EEZ, aggregate and precious coral can have 

an immediate economic impact if significant deposits and markets are found. Insular/lagoonal phosphorite and epithermal 

gold deposits could offer short- to intermediate-term resource 

potential if significant deposits are found. Cobalt-rich crusts 

should occur throughout the EEZ, but have limited resource 

potential because of low grades and tonnages. The other 

deposit types represent long-term or unknown resource potentials. Reconnaissance cruises dedicated to understanding the 

distribution, grade, and tonnage of all the potential resources 

are recommended. Only small parts of the EEZ have been 

mapped using multibeam bathymetric techniques and much 

larger parts need to be mapped to undertake viable exploration 

programs.

Selected References

Burnett, W.C., and Lee, A.I.N., 1980, The phosphate supply 

system in the Pacific region: GeoJournal, v. 4, p. 423-436.

Grigg, R.W., 1975, The commercial potential of precious corals 

in the western Caroline Islands, Micronesia: Sea Grant 

Technical Report UNIHI-SEAGRANT-AR-75-03, 14 p.

Hawkins, J.W., Bloomer, S.H., Evans, C.A., and Melchior, 

J.T., 1984, Evolution of intra-oceanic arc-trench systems: 

Tectonophysics, v. 102, p. 175-205.

Hein, J.R., 2004, Cobalt-rich ferromanganese crusts; global 

distribution, composition, origin and research activities, 

in Minerals other than polymetallic nodules of the 

international seabed area: Kingston, Jamaica, International 

Seabed Authority, Proceedings of a workshop held on 26-30 

June 2000, v. 1, p. 188-256.

Hein, J.R., Ahn, J-H., Wong, J.C., Kang, J.-K., and others, 

1992, Geology, geophysics, geochemistry, and deep-sea 

mineral deposits, Federated States of Micronesia; KORDIUSGS R.V. Farnella Cruise F11-90-CP: U.S. Geological 

Survey Open-File Report 92-218, 191 p.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Hein, J.R., Koschinsky, A., Halbach, P., Manheim, F.T., 

Bau, M., Kang, J.-K., and Lubick, N., L., 1997, Iron 

and manganese oxide mineralization in the Pacific, in

Nicholson, K., Hein, J.R., Bühn, B., and Dasgupta, S., eds., 

Manganese mineralization; geochemistry and mineralogy 

of terrestrial and marine deposits: Geological Society of 

London Special Publication 119, p. 123-138.

Hein, J.R., Moon, J.-W., Lee, K.-Y., Dowling, J.S., Kim, 

K.-H., Burrows, M., Park, S.H., Choi, Y.-J., Schuetze, 

A.A., Jung, H.S., Kin, H.-S., Lee, G.C., Park, C.-K., 

Son, S.K., and Park, C.Y., 1999, Co-rich Fe-Mn crusts 

from the Marshall Islands (Leg 1) and hydrothermal and 

hydrogenetic Fe-Mn deposits from Micronesia (Leg 2), 

KODOS 98-3 cruise, West Pacific: U.S. Geological Survey 

Open-File Report 99-412, 63 p.

Irving, E.M., 1950, Phosphate deposits of Angaur Island, 

Palau Islands: Report to the Military Geology Branch, U.S. 

Geological Survey, for the Intelligence Division, Office of 

the Engineer, General Headquarters, Far East Command, 99 

p.

Miller, W.R., Rytuba, J.J., Arnold, M.A., and Vercoutere, 

T.L., 1989, Investigation of the Rois Malk epithermal gold 

system, Republic of Palau: U.S. Geological Survey Bulletin 

1872, 85 p.

Stoddart, D.R., and Scoffin, T.P., 1983, Phosphate rock on 

 Republic of Belau (Formerly Palau)
16 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

coral reef islands, in Goudie, A.S., and Pye, K., eds., 

Chemical sediments and geomorphology: London, 

Academic Press, p. 369-400.

U.S. Army, Far East Command, 1956, Military geology of 

Palau Islands, Caroline Islands: Engineer intelligence 

dossier strategic study, Carolines, subfile 19, Analysis of the 

natural environment, 285 p.

Usui, A., and Someya, M., 1997, Distribution and composition 

of hydrogenetic and hydrothermal manganese deposits in 

the northwest Pacific, in Nicholson, K., Hein, J.R., Bühn, 

B., and Dasgupta, S., eds., Manganese mineralization; 

geochemistry and mineralogy of terrestrial and marine 

deposits: Geological Society of London Special Publication 

119, p. 177-198.
 Republic of Belau (Formerly Palau) 17

(Section on Guam begins on following pages.)
18 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

10,000

MARIANA

TRENCH

x

PARECE

 VELA

 BASIN

WEST

MARIANA

RID

G

E

Guam Island

Rota I.

Saipan I.

Aguijan I.

Tinian I.

Farallon de Medinilla I.

Anatahan I.

Sarigan I.

Guguan I.

Alamagan I.

Pagan I.

140o E

140o E

10o N

Hydrothermal vent sites

145o E

145oE

15o N

MARIANA

TRO

U

G

H

10o N

15o N

Figure 11. Bathymetric map of the Exclusive Economic Zone (EEZ) of Guam (“C” on fig.1); black line shows EEZ boundary. Contour interval is 

1,000 meters. The Federated States of Micronesia and the Commonwealth of the Northern Mariana Islands EEZs border the Guam EEZ to the 

south and north, respectively. Challenger Deep, (the greatest ocean depth (10,924 meters), is marked with an X.
19

Guam

Land area: 549 km2

EEZ area: 218,000 km2 (see fig. 11); 

 location shown by “C” on 

 figure 1

Political status: Organized, unincorporated 

 territory of the United States

Population: 166,090 (July 2004 estimate)

Island minerals: Aggregate, limestone

Island History

The Chamorro people first occupied Guam and may 

have migrated there from the Malay Archipelago. In 1521, 

Ferdinand Magellan was the first Westerner to visit Guam. 

Miguel Lopez Legaspi claimed Guam and several Mariana 

Islands for Spain in 1565; colonization began a few years 

later but was not well established until 1688. Most of the 

native Chamorro population died from disease and war 

during the following three centuries. U.S. forces took Guam 

in 1898 during the Spanish-American War, and it was ceded 

to the United States by Spain that year. Guam was under 

administration by the U.S. Navy until 1941, when it was 

captured by the Japanese. It was retaken by the United States 

three years later, and the U.S. Navy then renewed administration of the island.

The Guam Organic Act of 1950 conferred U.S. citizenship on the people of Guam and established local self government. At that time, the Department of the Interior took 

over administrative responsibility for Guam. Military installations on Guam are some of the most strategically important 

in the Pacific region. As the westernmost U.S. Territory, 

Guam is west of the International Date Line, and is one day 

ahead of the United States. Hence the slogan: “Where America’s Day Begins.”

Geography

Guam is the largest island in Micronesia and is the southernmost of the Mariana Islands. The northern half of Guam is 

composed of a relatively flat coralline limestone plateau about 

260 m above sea level, whereas the southern part is mountainous volcanic terrain with elevations up to 406 m (Mount 

Lamlam). Guam is largely surrounded by a fringing reef, but 

at the southern tip of Guam, a barrier reef and Cocos Island 

enclose Cocos Lagoon. Apra Harbor, located along the westcentral coast, is a large lagoon bounded by Cabras Island on 

the north and the Orote Peninsula on the south.

Geologic Setting

Guam is in the southernmost part of the volcanic arc that 

includes the Mariana Islands and many associated seamounts, 

several of which are volcanically active. The north-central part 

of the Guam EEZ is occupied by this volcanic arc (see fig. 11). 

The Mariana Arc started to develop about 40 million years 

ago by subduction of the Pacific Ocean crust underneath the 

Philippine Sea crust. Volcanic activity has occurred at various 

places along the arc since that time. To the south and southeast of Guam is the Mariana Trench, which has its deepest 

expression within the Guam EEZ—in fact, this is the deepest 

location in the global ocean. The trench is partly filled with 

sediment.

East of the Mariana Trench is the sediment-covered 

Pacific Ocean abyssal plain with several large Cretaceous 

(>65 million years old) seamounts that protrude through the 

sediment. The underlying crust in this area is Jurassic in age 

(>142 million years old) and is the oldest part of the Pacific 

Ocean crust. West of the Guam-Mariana Arc is the mostly 

sediment-covered Philippine Sea floor (a back-arc basin) with 

numerous seamounts, ridges, and basins that are less than 20 

million years old. In the part immediately west of the Mariana 

Arc is the Mariana Trough, an active back-arc spreading ridge. 

The West Mariana Ridge is a remnant (inactive) volcanic arc 

that separates the Mariana Trough from the Parece Vela Basin 

abyssal plain farther to the west, in the northwesternmost part 

of the Guam EEZ.

Offshore Mineral Deposits of Guam

The EEZ of Guam encompasses a variety of geologic, 

morphologic, and tectonic environments. Mineral deposits 

within these environments represent near- to long-term potential mineral resources that likely include:

• Cobalt-rich iron-manganese crusts on Cretaceous 

seamounts

• Iron-manganese nodules on abyssal plains

• Phosphorite deposits on Cretaceous seamounts

• Epithermal gold deposits on the active volcanic arc

• Hydrothermal manganese- and iron-oxide deposits on 

the active arc and back-arc

• Hydrothermal polymetallic sulfide/sulfate deposits on the 

active arc and back-arc

• Sand and gravel (aggregate) in nearshore environments

• Precious coral on the flanks of Guam and flanks and 

summit of seamounts

Cobalt-rich iron-manganese crusts likely are present 

east of the Mariana Trench on two large and many small Cretaceous seamount complexes located on Pacific Ocean crust. 

The distribution and morphology of Cretaceous seamounts in 

that region are poorly known, as are the distribution, grade, 

and tonnage of crusts on those seamounts. Data for crusts 

from nearby seamounts indicate that crusts on Cretaceous seamounts within the Guam EEZ are likely to be thick and have 

high concentrations of cobalt, nickel, and especially platinum. 

These deposits may represent an intermediate-term resource 

 Guam
20 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

potential for cobalt, titanium, cerium, nickel, platinum, and 

other rare-earth elements and metals. Iron-manganese crusts 

recovered from the Guam sector of the Mariana Arc and West 

Mariana remnant arc are too thin and have cobalt contents too 

low to be considered economically viable in the foreseeable 

future. A research cruise is required to sample and map the distribution of crusts on the Cretaceous seamounts in the Guam 

EEZ before a resource evaluation of those crusts can be made.

Iron-manganese nodules have been photographed on 

the abyssal plain east of Guam and also west of Guam, on the 

deepest parts of the Philippine Sea floor. Judging from these 

few photographic stations, nodule coverage is apparently low. 

However, not enough data exist to determine nodule distribution, grade, or tonnage. A research cruise is required to sample 

and map the distribution of nodules in the Guam EEZ before a 

resource evaluation can be made.

Phosphorite should occur on the same Cretaceous seamounts as the iron-manganese crusts. However, the distribution and grade are not known. These deposits are typically 

either small, high-grade deposits or more widespread, lowgrade deposits. This deep-water deposit type may have a longterm resource potential.

Gold deposits of epithermal origin are known to occur 

on islands in the Yap and Palau volcanic arcs to the south and 

southwest of Guam. Favorable geologic offshore sites for epithermal gold are probable along the intersections of faults and 

fracture zones and along the Guam-Mariana Arc in submerged 

calderas. Exploration will be required to delineate potential 

sites for epithermal gold deposits. If epithermal gold does 

occur offshore in deep water, it would offer an intermediateterm resource potential.

Manganese oxide of hydrothermal origin is known to 

occur extensively along the Mariana volcanic arc, along the 

spreading axis of the Mariana Trough, and on the West Mariana Ridge. Manganese oxide cements sediments and forms 

stratabound layers within the sediments and rocks. In places, 

the manganese deposits have high contents of one or more of 

the metals copper, nickel, molybdenum, zinc, and chromium. 

Because large deposits of these metals are currently available 

on the continents, this deposit type offers only a long-term 

resource potential. However, it may be found that other metals 

of economic importance are enriched in the manganese-oxide 

deposits in volcanic arcs; chromium-rich deposits were only 

recently discovered in the Yap Arc. These low-temperature 

hydrothermal deposits may also be indicators of nearby hightemperature polymetallic sulfide deposits.

Polymetallic sulfides, sulfates, and sulfur of hydrothermal origin have been found north of Guam at several sites 

along the active Mariana Arc. Hydrothermal activity at seven 

additional sites have been reported, but they have not been 

surveyed for polymetallic sulfide deposits. A large gold-rich 

deposit was found in 1999 in a volcanic crater (caldera) in the 

Izu-Bonin Arc, which is a continuation of the Mariana Arc to 

the north. These deposits and hydrothermal sites are outside 

the Guam EEZ, the closest being 37 kilometers north of the 

EEZ boundary.

Two recently discovered hydrothermal sites with associated sulfides have been found south of Guam within its EEZ 

(fig. 11). One site is located along the spreading axis of the 

Mariana Trough and the other is a seamount located along 

an offset of the southern most part of the Mariana Arc. These 

deposits have been discovered only recently and have not 

yet been analyzed for gold, silver, and base-metal contents. 

Polymetallic sulfides from the Okinawa trough back-arc 

basin located to the west of the Mariana Arc have high gold 

and silver contents. Polymetallic sulfide deposits have been 

explored for in the Guam EEZ in a reconnaissance fashion, 

and more sites similar to the two recently discovered are likely 

to exist in the central region of the EEZ. If gold- and silverrich polymetallic sulfides are found within the Guam EEZ, 

they could offer a near-term resource potential.

Sand and gravel deposits occur in shallow water adjacent 

to most of the Guam coastline. Large and exploitable deposits occur in Cocos Lagoon to the south of Guam and in Apra 

Harbor. Exploitation of these or smaller deposits along the 

coast would have to address environmental concerns. Numerous on-land limestone and volcanic rock outcrops in relatively 

remote areas offer a viable alternative source for building 

aggregate. Beach sand also provides a potential source for 

building aggregate, but again its exploitation raises environmental issues. Fluvial aggregate and beach-placer deposits are 

very limited on Guam. Sand and gravel in Cocos Lagoon and 

Apra Harbor offer a near-term resource potential.

Precious coral is found at shallow to intermediate water 

depths at many places around Guam. Surveys for black and 

red/pink coral were carried out in 1975, but no commercial 

grade deposits were indicated on the basis of the few samples 

collected. However, the deeper water areas (>400 m) around 

Guam and seamounts east of the Mariana Trench have not 

been surveyed; promising targets occur to depths of 1,500 m 

in both areas. Regulations are already in place concerning the 

exploitation of this resource. Precious coral has an immediate economic market, but exploitation must not deplete the 

resource beyond the point at which it can renew itself.

Summary

Several reconnaissance cruises have located and investigated hydrothermal sites within the Guam EEZ for scientific 

purposes. Reconnaissance exploration for sand and gravel and 

for precious coral has also taken place. Aggregate, precious 

coral, and gold- and silver-rich hydrothermal polymetallic 

sulfides have an immediate economic market. Cobalt-rich 

crusts may have an intermediate-term resource potential, but a 

survey of the Cretaceous seamounts in the southeastern part of 

the EEZ must be carried out. Iron-manganese nodules, hydrothermal manganese, base-metal hydrothermal polymetallic sulfides, phosphorite, and epithermal gold offer intermediate to 

long-term resource potentials. Available bathymetric maps of 

the Guam EEZ are not good enough for exploration purposes, 

and the EEZ should be mapped using multibeam bathymetric 

and sidescan sonar techniques.
21

Select References

Grigg, R.W., and Eldredge, L.G., 1975, The commercial 

potential of precious corals in Micronesia; Part 1, 

the Mariana Islands: University of Guam, Sea Grant 

Publication, UGSG-75-01.

Hein, J.R., Fleishman, C.L., Morgenson, L.A., Bloomer, 

S.H., and Stern, R.J., 1987, Submarine ferromanganese 

deposits from the Mariana and Volcano volcanic arcs, 

West Pacific: U.S. Geological Survey Open-File Report 

87-281, 67 p.

Hein, J.R., Koschinsky, A., Halbach, P., Manheim, F.T., Bau, 

M., Kang, J.-K., and Lubick, N., 1997, Iron and manganese 

oxide mineralization in the Pacific, in Nicholson, K., 

Hein, J.R., Bühn, B., and Dasgupta, S., eds., Manganese 

mineralization; geochemistry and mineralogy of terrestrial 

and marine deposits: Geological Society of London Special 

Publication No. 119, p. 123-138.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

National Oceanic and Atmospheric Administration, Submarine 

ring of fire 2004—Mariana Arc: at http://oceanexplorer.

noaa.gov/explorations/04fire/welcome.html, accessed 

September 2005.

Palfreyman, W.D., Doutch, H.F., Brathwaite, R.L., Masaharu, 

K., Piper, D.Z., Swint-Iki, T.R., McCoy, F.W., Sullivan, 

L.G., Manheim, F.T., and Lane-Bostwick, C.M., 1996, 

Mineral-resources map of circum-Pacific region, southwest 

quadrant: U.S. Geological Survey Circum-Pacific Map 

Series, 1 sheet, scale 1:10,000,000, with booklet, 66 p.

Piper, D.Z., McCoy, F.W., and Swint, T.R.,1985, Manganese 

nodules, sea floor sediment, and sedimentation rates for 

the circum-Pacific region: Tulsa, Oklahoma, American 

Association of Petroleum Geologists, 1 sheet, scale 

1:17,000,000.

Schulz, M.S., and Hein, J.R., 1991, Petrography and chemistry 

of hydrothermal manganese oxyhydroxides from the 

Mariana and Izu-Bonin volcanic arcs, West Pacific: U.S. 

Geological Survey Open-File Report 91-557, 80 p.

Tracey, J.I., Jr., Schlanger, S.O., Stark, J.T., Doan, D.B., 

and May, H.G., 1964, General geology of Guam: U.S. 

Geological Survey Professional Paper 403-A, 104 p.

Usui, A., and Someya, M., 1997, Distribution and composition 

of marine hydrogenetic and hydrothermal manganese 

deposits in the northwest Pacific, in Nicholson, K., 

Hein, J.R., Bühn, B., and Dasgupta, S., eds., Manganese 

mineralization; geochemistry and mineralogy of terrestrial 

and marine deposits: Geological Society of London Special 

Publication No. 119, London, p. 177-198.

 Selected References
22 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Figure 12. Bathymetric map of the Exclusive Economic Zone (EEZ) of Howland and Baker Islands (“D” on fig.1); black line shows EEZ boundary. 

Contour interval is 500 meters. The Kiribati EEZ borders the Howland and Baker Islands EEZ to the southeast.

6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

7,000

Phoenix Islands

(Rawaki)

Winslow 

Reef

Howland

Island Baker Island

Titov 

Seamount

180o W

180o W

175o W

175o W

170o W

170o W

5o S

0o

5o N

Fe-Mn crust sample sites

5o S

0o

5o N
23

Howland and Baker Islands

Land area: 1.6 km2 (Howland), 1.4 km2 

 (Baker)

EEZ area:	 	 425,700 km2 (see fig. 12); 

 location shown by “D” on 

 figure 1

Political status: Unincorporated territory of 

 the United States

Population: Uninhabited

Island minerals: Phosphorite/guano

Island History

Captain George B. Worth on the U.S. whaling ship Oeno

discovered these islands in 1822. They were visited subsequently 

in 1828 by Captain Daniel McKenzie of the U.S. whaler Minerva 

Smyth, in 1832 and 1839 by Michael Baker of the whaler Gideon 

Howland, and in 1842 by Captain George E. Netcher of the U.S. 

whaler Isabella. Alfred G. Benson and Charles H. Judd took 

formal possession of the islands (as well as Jarvis Island) in 1857 

in the name of the American Guano Company of New York. Rich 

guano deposits were mined from 1850 to 1891 and in 1857 the 

United States claimed the islands on the basis of the Guano Act of 

August 18, 1856. The Guano Act stated that “when any citizen of 

the United States discovers a guano deposit on any island, rock, 

or key, not within the lawful jurisdiction of any other government, 

and takes peaceable possession thereof, and occupies the same 

island, rock, or key, it appertains to the United States.” In the later 

part of the 19th century, the guano industry gradually disappeared 

on Howland and Baker Islands. The islands were then barren 

outposts until the era of aviation began in the 1930s. The United 

States reasserted its claim to the islands in 1934. A few colonists 

occupied the islands in 1936, but they were removed following 

Japanese attacks on the islands in 1942. U.S. military personnel occupied the islands during World War II. The islands have 

remained unoccupied since that time, but they are visited annually by U.S. Fish and Wildlife personnel because the islands are a 

National Wildlife Refuge.

Howland Island played a role in the tragic disappearance 

of Amelia Earhart and Fred J. Noonan during their around-theworld flight in 1937. They left Lae, New Guinea, on July 2, 

1937, headed for Howland Island, but were never seen again. 

Numerous speculations have been put forward as to their fate. 

The Amelia Earhart lighthouse on Howland Island was partly 

destroyed during World War II, but it was later rebuilt in her 

memory.

Geography

Howland and Baker Islands lie just north of the equator, 

about 3,056 kilometers southwest of Hawai’i. They are separated by 66 kilometers. Howland Island, measuring about 3.2 

by 0.8 kilometers, is a low-lying (maximum 6 meters), nearly 

flat, sandy coral island surrounded by a narrow fringing 

reef. Baker Island, measuring about 1.6 by 1.4 kilometers, 

is also a low-lying (maximum 8 meters), nearly flat (somewhat depressed in the central area) coral island surrounded 

by a fringing reef. They are both reef islands consisting of 

low-lying accumulations of reef debris deposited on top of 

a reef platform without a lagoon. Both islands are described 

as equatorial, with scant rainfall, constant wind, and burning 

sun.

Geologic Setting

Howland and Baker Islands are composed of coral-reef 

platforms sitting atop Cretaceous (~120-75 million years old) 

volcanoes. The Howland-Baker EEZ contains about 10 other 

moderate-sized and many small Cretaceous seamounts that 

are either without coral reefs or capped by submerged reefs. 

At least one of the seamounts, Winslow Reef on the southeast 

boundary line of the EEZ, has a submerged coral-reef cap with 

the summit at about 1,500-meter water depth. Otherwise, the 

sea-floor topography of the EEZ is dominated by a sedimentcovered abyssal plain deeper than 5,000 meters.

Offshore Mineral Deposits of Howland and 

Baker Islands

The EEZ boundary to the south is shared with that of 

Kiribati’s Phoenix Islands. Immediate- to long-term potential mineral resources occur within the EEZ of Howland and 

Baker Islands. Insular phosphorite was mined on both islands 

from 1850-1891 Mineral deposits likely to occur within the 

EEZ include:

• Cobalt-rich iron-manganese crusts on Cretaceous 

seamounts

• Iron-manganese nodules on the deep abyssal plain

• Phosphorite deposits on Cretaceous seamounts

• Insular phosphorite on Howland and Baker Islands

• Hydrothermal iron and manganese deposits on seamounts 

• Shallow-water sand and gravel (aggregate) on and adjacent 

to Howland and Baker Islands

• Shallow- to deep-water precious coral on seamounts and 

islands slopes

Cobalt-rich iron-manganese crusts have been sampled 

from two seamounts within the Howland-Baker EEZ. Two 

dredge hauls taken in 1985 by German scientists recovered 

samples from Titov seamount, located southeast of Baker 

Island. The crust samples from those dredges have very high 

cobalt (mean 0.97 percent; maximum 1.3 percent) and nickel 

(mean 0.65 percent; maximum 0.88 percent) contents, among 

the highest in any Pacific EEZ. Crusts were collected from a 

seamount at the central-west margin of the EEZ, but the much 

 Howland and Baker Islands
24 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

older chemical data for that sample are of suspect quality and 

not considered here.

The distribution of crust deposits having high cobalt and 

nickel contents within the EEZ is not known. The seamounts in 

the EEZ are relatively small, or, for the plateau south of Baker 

Island, in too deep water to offer good prospects for a significant 

resource potential. Consequently, these deposits likely represent an intermediate- to long-term resource potential for cobalt, 

nickel, and possibly other metals, although the very high metal 

contents do warrant an additional sampling program.

Iron-manganese nodules likely occur on the sediment 

surface of the deep-water abyssal plain that characterizes most 

of the EEZ. The few age determinations of siliceous ooze 

from the abyssal plain suggest a slow rate of sediment accumulation, which would favor high nodule coverage and high 

nickel and copper contents. Very little work has been done on 

these deposits, however, and nodule distribution and grade 

have not been determined. Past work by Japanese scientists in 

nearby areas indicates that nodule coverage may be extensive 

and copper and nickel contents may be high to very high. If 

areas having nodules of favorable density and grades can be 

located within the Howland and Baker Islands EEZ, then these 

nodules would offer an intermediate-term resource potential 

because of the large area of sea floor represented by abyssal 

plain. It is recommended that an exploration program for nodules be carried out.

Phosphorite deposits on seamounts have been sampled 

from two dredges collected by German scientists in 1985. Phosphorite is abundant and of high grade in those dredges, indicating that it might be widespread within the EEZ on seamounts 

and on the plateau south of Baker Island. These deposits are 

typically either small, high-grade deposits or more widespread, 

low-grade deposits. This deposit type may have a long-term 

resource potential.

Insular phosphorite deposits occur on Howland and 

Baker Islands and were mined from 1850 to 1891. About 

100,000 tonnes and 250,000 tonnes of insular phosphorite were 

mined from Howland Island and Baker Island, respectively. 

Reserves were exhausted, but further exploration for buried 

deposits and research to determine their origin are warranted. 

This work should include sampling of island outcrops and a 

drilling program on the carbonate platforms. Exploration and 

exploitation of additional deposits is unlikely, however, because 

of the islands’ status as National Wildlife Refuges.

Hydrothermal iron and manganese deposits are likely 

to occur scattered throughout the region, but have not as yet 

been sampled. This deposit type may have a long-term resource 

potential.

Shallow-water and insular aggregate for construction 

consists of sand and gravel composed of coral and shell. Construction materials are ubiquitous on these islands, which are 

composed predominantly of unconsolidated carbonate (CaCO3

) 

sand and gravel. The east coast of Howland Island consists of 

coral rubble, whereas the west coast consists of beach sand. 

Exploration for nearshore and island sources of sand and gravel 

may identify deposits that can be extracted for local construction without damage to the environment. In general, construction 

materials are common on this type of island, but it may be difficult to locate deposits where exploitation will not accelerate land 

loss, shoreline erosion, or result in permanent habitat loss. Nearshore deposits would be limited to the reef terrace (as much as 2 

kilometers wide) surrounding the islands, which is submerged in 

4 to 20 meters of water. Armor stone for use in revetments and 

shore protection can be mined from the reef flat of the narrow 

fringing reef (50 to 250 meters wide) and from beachrock deposits. Designation of these uninhabited islands as National Wildlife 

Refuges will limit development of aggregate resources.

Shallow- to deep-water precious coral may occur on seamounts and the island slopes within the Howland-Baker EEZ. 

Shallow-water black coral species typically occur in areas of 

steep rock faces swept by strong currents in water depths greater 

than 20 meters. Howland and Baker Islands should have numerous potential sites for precious coral. However, the distribution, 

abundance, and the resource potential of precious coral are 

unknown. A systematic exploration program is needed to delineate this resource. If important deposits are found, they would 

have an immediate economic market.

Summary

Aggregate, insular phosphorite, and precious coral could 

have an immediate economic impact if significant deposits 

and markets are found. Exploitation of these commodities 

would require maintenance of environmental and ecological 

quality and will be limited by the presence of wildlife refuges. 

Iron-manganese nodules offer an intermediate-term resource 

potential, whereas the other deposit types represent long-term 

or unknown resource potentials. Research cruises dedicated 

to understanding the distribution, grade, and tonnage of these 

potential resources are recommended.

Selected References

Halbach, P.E., Sattler, C.D., Teichmann, F., and Wahsner, 

M., 1989, Cobalt-rich and platinum-bearing manganese 

crust deposits on seamounts; nature, formation, and metal 

potential: Marine Mining, v. 8, p. 23-39.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Palfreyman, W.D., Doutch, H.F., Brathwaite, R.L., Masaharu, 

K., Piper, D.Z., Swint-Iki, T.R., McCoy, F.W., Sullivan, 

L.G., Manheim, F.T., and Lane-Bostwick, C.M., 1996, 

Mineral-resources map of circum-Pacific region, southwest 

quadrant: U.S. Geological Survey Circum-Pacific Map 

Series, 1 sheet, scale 1:10,000,000, with booklet, 66 p.

Piper, D.Z., McCoy, F.W., and Swint, T.R., 1985, Manganese 

nodules, sea floor sediment, and sedimentation rates for 

the circum-Pacific region: Tulsa, Oklahoma., American 
25

Association of Petroleum Geologists, 1 sheet, scale 

1:17,000,000.

Piper, D.Z., Loebner, B., and Ahron, P., 1991, Physical and 

chemical properties of the phosphate deposit on Nauru, 

the equatorial Pacific, in Riggs, S., and Burnett, W., eds., 

Phosphate deposits of the world, v. III: London, Cambridge 

University Press, p. 178-194.

Usui, A., ed., 1994, Marine geology, geophysics and 

manganese nodule deposits in the Penrhyn Basin, South 

Pacific, August-October 1983 (Hakurei-Maru Cruise GH83-

3): Tsukuba, Japan, Geological Survey of Japan Cruise 

Report No. 23, 246 p.

 Howland and Baker Islands
26 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

Jarvis Island

NORTH

 PENRHYN

 BASIN

LINE ISLANDS

Kiritimati I.

(Christmas I.)

NOVA-CANTON RIDGE

Tabuaeran I.

(Fanning I.)

Teraina I.

(Washington I.)

165o W

165o W

160o W

160o W

155o W

155o W

5o S 5o S

0o 0o

5o N 5o N

Fe-Mn crust sample site

Figure 13. Bathymetric map of the Exclusive Economic Zone (EEZ) of Jarvis Island (“E” on fig.1); black line shows EEZ boundary. Contour interval is 500 meters. The Kiribati EEZ borders the Jarvis Island EEZ to the north, east, and southeast.
27

Jarvis Island

Land Area: 4.5 km2

EEZ Area: 323,100 km2 (see fig. 13); 

 location shown by “E” on 

 figure 1

Political Status: Unincorporated territory of 

 the United States 

Population: Uninhabited

Island Minerals: Phosphorite/guano

Island History

Jarvis Island was discovered in 1821 by Captain Brown 

on the British ship Eliza Francis. Alfred G. Benson and 

Charles H. Judd took formal possession of the island in 1857 

in the name of the American Guano Company of New York. 

Later that year, Commander Charles Henry Davis of the USS 

St. Mary surveyed the island and formally claimed it for the 

United States. Jarvis Island was mined for guano in the 

late 1800s. Under the Guano Act of 1856 (see the section on 

Howland-Baker Islands for a description of the Guano Act), 

it became a U.S. possession. Jarvis was abandoned in 1879 

after many tonnes of guano had been removed. The United 

Kingdom annexed the island in 1889, but did not further 

develop the mining operations. In 1906 it was leased to the 

Pacific Phosphate Company of London, but again mining 

was not further developed. The United States reoccupied and 

reclaimed Jarvis in 1935 and it was placed under the jurisdiction of the Department of the Interior on May 13, 1936 

(Executive Order 7368). The new colonists were evacuated 

from the island in 1942 following attacks by Japanese forces, 

and the island has remained mostly uninhabited since then. 

In 1957-1958, Millersville, on the western side of the island, 

was occupied by scientists during the International Geophysical Year. Since June 1974, the island has been administered 

by the U.S. Department of the Interior Fish and Wildlife Service as part of the National Wildlife Refuge system.

Geography

Jarvis Island is located just south of the equator about 

1,850 kilometers east of Howland and Baker Islands. The 

island is about 3.2 kilometers long and 1.6 kilometers wide. 

Jarvis consists of a relatively flat (mostly 4.6 to 6.1 meters 

high; maximum 7 meters), sandy, coral island platform with 

a lower central basin and a narrow fringing reef. A submarine 

terrace (water depth 4 to 20 meters) extends to one kilometer 

offshore. The island is described as tropical with little rainfall, 

constant wind, and burning sun.

Geologic Setting

Jarvis Island is part of the Line Islands linear volcanic 

chain, most of which is part of Kiribati. This linear array of 

islands and seamounts has been considered a hot-spot trace 

similar to that of Hawai’i, but recent work has shown that the 

age of volcanoes is nearly the same along major segments of 

the chain. This suggests nearly coeval volcanism along a preexisting zone of weakness. A few small to moderate-size seamounts occur within the Jarvis Island EEZ, with ages of about 

70 to 40 million years. The dominant sea-floor topography is 

an abyssal plain more than 5,000 meters deep. Sediment in the 

south and west parts of the EEZ is siliceous ooze, whereas in 

the north and east it is carbonate ooze.

Offshore Mineral Deposits of Jarvis Island

The EEZ boundary to the north and east is shared with 

Kiribati’s Line Islands. Immediate- to long-term potential mineral resources may occur within the EEZ of Jarvis Island. There 

have been no marine mineral surveys within the Jarvis Island 

EEZ and only one mineral deposit sample has been collected 

there. The sea-floor bathymetry and resource potential are 

likely to be comparable to those of the Howland-Baker Islands 

EEZ. Mineral deposits likely to occur within the EEZ include:

• Cobalt-rich iron-manganese crusts on sea 

 mounts

• Iron-manganese nodules on the deep abyssal 

 plain

• Phosphorite deposits on seamounts

• Insular phosphorite on Jarvis Island

• Hydrothermal iron and manganese deposits 

 on seamounts 

• Shallow-water sand and gravel (aggregate) on 

 and adjacent to Jarvis Island

• Shallow- to deep-water precious coral on 

seamounts and island flanks

Cobalt-rich iron-manganese crusts have not been studied within the Jarvis Island EEZ. One sample collected and 

analyzed in the 1960s is described as a manganese-coated rock 

and may be a nodule rather than a crust, as indicated by its 

chemistry and deep-water collection site (5,080 meters). This 

sample has relatively high nickel (0.77 percent) and copper 

(0.54 percent) contents, and low cobalt (0.15 percent). If this 

is a nodule, the nickel-plus-copper content of 1.31 percent 

is above the cutoff grade of 1.18 percent (see discussion in 

appendix 2). Work in the Line Islands to the east of Jarvis by 

British scientists indicates that crusts rich in cobalt and nickel 

should occur on seamounts in the Jarvis Island EEZ. However, 

the seamounts in the EEZ are relatively few, small, and too 

deep to offer a promising resource potential for the foreseeable 

future. These deposits likely represent a long-term resource 

potential for cobalt, nickel, and other metals.

 Jarvis Island
28 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Iron-manganese nodules likely occur on the sediment 

surface of the deep-water abyssal plain that characterizes most 

of the EEZ, but no surveys have been done and only one possible sample has been analyzed (see discussion for cobalt-rich 

crusts above). If the nickel-plus-copper content (1.31 percent) 

of that nodule is representative of nodules in the EEZ, then 

they would be considered as a potential resource. Work by 

Japanese and British scientists in nearby areas indicates that 

nodule coverage may be extensive and copper and nickel 

contents may be high to very high. These findings are in agreement with the occurrence of siliceous ooze to the south and 

west of the island and the low sediment accumulation rate. If 

areas of favorable nodule density and grades can be located 

within the Jarvis Island EEZ, then these nodules would offer 

an intermediate-term potential because of the large area of sea 

floor represented by abyssal plain. It is strongly recommended 

that an exploration program for nodules be carried out.

Phosphorite deposits on seamounts within the Jarvis 

Island EEZ have not been sampled. However, samples collected 

from seamounts in adjacent areas indicate that phosphorite 

might be widespread within the EEZ. These deposits are typically either small, high-grade deposits or more widespread, lowgrade deposits that may have a long-term resource potential.

Insular phosphorite deposits of high grade are known to 

occur on Jarvis Island. In the late 1800s, about 200,000 tonnes 

of phosphorite was mined on the island; the amount remaining 

is unknown. An exploration program for insular phosphorite 

should include sampling of island outcrops and a drilling program on the carbonate platform. Discovery of rich phosphorite 

deposits could have an immediate economic impact. If viable 

deposits are found, however, mining would take place only 

as the result of extreme need because the island is a National 

Wildlife Refuge.

Hydrothermal iron and manganese deposits are likely 

to occur scattered throughout the region, but have not as 

yet been sampled. This deposit type may have a long-term 

resource potential.

Shallow-water and insular aggregate for construction consists of sand and gravel composed of coral and shell. 

Construction materials are ubiquitous on reef islands, because 

they are predominantly composed of unconsolidated sand and 

gravel. Armor stone for use in revetments and shore protection 

can be mined from the reef flat of the narrow fringing reef and 

from beachrock deposits. Exploration for nearshore and island 

sand and gravel should identify deposits that can be used for 

local construction. Nearshore deposits would be limited to the 

submerged reef terrace surrounding the island. In general, construction materials are common on this type of island, but it is 

important to identify deposits where exploitation will not accelerate land loss or shoreline erosion, nor result in permanent 

habitat loss. The designation of this uninhabited island as a 

National Wildlife Refuge will limit the extraction of aggregate.

Shallow- to deep-water precious coral may occur 

on seamounts and the island flanks within the Jarvis EEZ. 

Because its distribution and abundance are unknown, a 

systematic exploration program is required to evaluate its 

resource potential. If deposits are found, they could have an 

immediate economic market.

Summary

Aggregate, precious coral, and especially insular phosphorite could have an immediate economic impact if significant deposits and markets are found. Exploitation of these 

commodities would require addressing environmental and 

ecological issues. Nickel- and copper-rich nodules may offer 

an intermediate-term resource potential. The other deposit 

types represent long-term or unknown resource potential. 

Exploration directed to understanding the distribution, grade, 

and tonnage of these potential resources is recommended. The 

designation of Jarvis Island as a National Wildlife Refuge will 

limit activity in the vicinity of the island.

Selected References

Aplin, A.C., and Cronan, D.S., 1985, Ferromanganese oxide 

deposits from the central Pacific Ocean, I. Encrustations 

from the Line Islands Archipelago: Geochimica et 

Cosmochimica Acta, v. 49, p. 427-436.

Corvalan, D.J., Guild, P.W., Piper, D.Z., Swint-Iki, T.R., 

McCoy, F.W., Sullivan, L.G., Manheim, F.T., LaneBostwick, C.M., and Luepke, G., 1996, Mineral-resources 

map of the circum-Pacific region, southeast quadrant: U.S. 

Geological Survey circum-Pacific Map Series CP-42, scale 

1:10,000,000, with booklet, 30 p.

Davis, A.S., Gray, L.B., Clague, D.A., and Hein, J.R., 2002, 

The Line Islands revisited; new 40Ar/39Ar geochronologic 

evidence for episodes of volcanism due to lithospheric 

extension: Geochemistry, Geophysics, Geosystems, v. 3, no. 

3, 10.1029/2001GC000190, 28 p.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Palfreyman, W.D., Doutch, H.F., Brathwaite, R.L., 

Masaharu, K., Piper, D.Z., Swint-Iki, T.R., McCoy, F.W., 

Sullivan, L.G., Manheim, F.T., and Lane-Bostwick, C.M., 

1996, Mineral-resources map of circum-Pacific region, 

southwest quadrant: U.S. Geological Survey CircumPacific Map Series,1 sheet, scale 1:10,000,000, with 

booklet, 66 p.

Usui, A., ed., 1994, Marine geology, geophysics and 

manganese nodule deposits in the Penrhyn Basin, South 

Pacific, August-October 1983 (Hakurei-Maru Cruise GH83-

3): Tsukuba, Japan, Geological Survey of Japan Cruise 

Report No. 23, 246 p.
 Jarvis Island 29

(Section on Johnston Atoll begins on following pages.)
30 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

170n W

170n W

165n W

165n W

15n N

20n N

Fe-Mn crust sample sites

Johnston

Atoll

HORIZON GUYOT

KARIN RIDGE

KELI RIDGE

15n N

20n N

Hydrothermal ironstone sample sites

Fe-Mn nodule sample sites

BLACK FRIDAY

RIDGE

SoJIR

Figure 14. Bathymetric map of the Exclusive Economic Zone (EEZ) of Johnston Atoll (“F” on fig.1); black line shows EEZ boundary. Contour 

interval is 500 meters. SoJIR is South Johnston Island Ridge.
31

Johnston Atoll 

Land area: 2.8 km2

EEZ area: 449,300 km2 (see fig. 14); 

location shown by “F” on 

 figure 1

Political status: Unorganized, unincorporated 

 territory of the United States

Population: Average 800 U.S. military 

 and civilian personnel (July 

 2003 estimate)

Island minerals: Phosphorite/guano

Island History

Johnston Atoll was sighted in 1796 by the U.S. Brig Sally

under the command of Joseph Pierpoint, but it was named 

for Captain James Johnston of the HBMS Cornwallis, who 

claimed its official discovery on December 14, 1807. In March 

1858, the captain of the U.S. schooner Palestine claimed the 

island for the United States, and three months later the island 

was claimed by Captain Watson of the Hawaiian schooner 

Kalama for the Kingdom of Hawai’i. Two crew members 

from the schooner Palestine were left on the island to collect 

phosphate. The island was annexed to the United States as a 

guano island under the Guano Act of 1856 (see description 

under Howland-Baker Islands). A large amount of guano was 

removed from the atoll between the late 1850s and the early 

1900s. The atoll did not have a permanent population until 

1936.

On July 29, 1926, President Calvin Coolidge established 

Johnston Atoll as a Federal bird refuge by Executive Order 

4467 and placed it under the control of the U.S. Department 

of Agriculture. On December 29, 1934, Executive Order 6935 

by President Franklin Roosevelt transferred control of Johnston Atoll jointly to the U.S. Navy to establish an air station 

and also to the Department of the Interior to administer the 

bird refuge. In 1936, the U.S. Navy began developing a seaplane base, an airstrip, and refueling facilities. These facilities 

served as an important link between Hawai’i and the western 

Pacific during World War II. The atoll was fortified during the 

war and used as a supply point for submarines.

The Secretary of the Navy agreed to transfer operational 

control of Johnston Atoll to the U.S. Air Force on July 1, 

1948, to be used for nuclear testing. Johnston Atoll was used 

as the launch site for atmospheric nuclear weapons tests in 

the 1950s and 1960s. In the 1960s, three missiles carrying 

nuclear warheads were destroyed by nonnuclear explosions, 

one on the launch pad and two at altitudes of 9 and 33 kilometers, which spread plutonium- and uranium-containing 

particles over the atoll. The Department of the Air Force 

signed an agreement with the Defense Nuclear Agency on 

July 1, 1973, to administer and host-manage the island. In 

the 1990s, the atoll was used as a site for a Chemical Agent 

Disposal System (JACADS) that incinerated chemical weapons. The Atoll is now administered by the U.S. Defense 

Threat Reduction Agency and managed cooperatively with 

the U.S. Fish and Wildlife Service as part of the National 

Wildlife Refuge system.

Geography

Johnston Atoll is located about 1,330 kilometers westsouthwest of Honolulu. The atoll is highly modified and consists of one large island (Johnston Island) and several small 

islets (Akau, Sand, Hikina) in a lagoon flanked by a barrier 

reef only on the northwest margin of the atoll.Johnston and 

Sand Islands are natural islands that have been significantly 

expanded by coral dredging, whereas Akau and Hikina 

Islands are entirely manmade from coral dredged from the 

reef. Johnston Island, a flat sand-and-coral island with a highest elevation of about 4 to 5 meters, is flat because it was 

leveled for construction purposes, such as the building of a 

runway.

Geologic Setting

Johnston Atoll is the northernmost island in the Line 

Islands chain. All but the northwest part of the atoll barrier 

reef has subsided, and reef growth has been unable to keep 

pace with the rate of subsidence; it may be in transition from 

an atoll to a seamount. The volcanic pedestal below Johnston 

Atoll is about 71 million years old. The Johnston Atoll EEZ 

consists of a complex array of Cretaceous (86 to 69 million 

years old) volcanic ridges and seamounts. Karin Ridge is 86 

to 81 million years old and is the largest volcanic edifice in the 

EEZ. It trends northwest-southeast and is continuous with the 

Line Islands ridge to the southeast of the EEZ. Karin Ridge 

has been sampled for cobalt-rich iron-manganese crusts during 

two USGS cruises. Horizon Guyot, an elongate flat-topped 

seamount, trends northeast-southwest, nearly at right angles to 

Karin Ridge, and is 82 million years old. Horizon Guyot has 

also been sampled for crusts on USGS and other cruises. Keli 

Ridge is 72 to 69 million years old and trends more east-west 

than Karin Ridge. Keli Ridge has been sampled for crusts 

during two German cruises. The flat summit of Horizon 

Guyot is sediment covered, whereas the summits of Karin and 

Keli Ridges are mostly free of sediment.

Many other large and small seamounts occur within the 

EEZ (see fig. 14), but they have not been sampled. Although 

the Johnston Atoll EEZ has been relatively well studied for 

iron-manganese crusts, the majority of the seamounts in the 

EEZ have not been sampled. About 40 percent of the EEZ 

is dominated by sediment-covered abyssal plains deeper than 

5,000 meters.

 Johnston Atoll
32 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Offshore Mineral Deposits of Johnston Atoll

Cobalt-rich iron-manganese crusts and seamount phosphorites have been systematically sampled and studied at 

many sites within the Johnston Atoll EEZ by U.S. research 

cruises and by joint U.S.-German, U.S.-Japanese, and U.S.-

Russian cruises. However, other mineral-deposit types have 

not been systematically surveyed in the EEZ, which likely 

contains immediate- to long-term potential mineral resources. 

Guano phosphorite was mined on the island from 1850 to 

1900. Mineral deposits that do or are likely to occur within the 

EEZ include:

• Cobalt-rich iron-manganese crusts on seamounts and 

 ridges

• Iron-manganese nodules on the deep abyssal plains

• Phosphorite deposits on seamounts and ridges

• Insular and lagoonal phosphorite on Johnston Atoll

• Hydrothermal iron and manganese deposits on sea 

 mounts and ridges

• Shallow-water sand and gravel (aggregate) on Johnston 

Atoll

• Shallow- to deep-water precious coral on seamounts, 

ridges, and the island slopes

Cobalt-rich iron-manganese crusts have been relatively 

extensively studied within the Johnston Atoll EEZ. This EEZ 

contains widespread crust deposits with high contents of 

cobalt and nickel and moderate contents of platinum. Both 

crust thicknesses and grades exceed cut-off levels for potential 

mining (see appendix 2). The U.S. Minerals Management Service completed an environmental impact statement for crust 

mining in the EEZ of Johnston Atoll and Hawaii. In 1981 and 

again in 1984, the German ship R.V. Sonne sampled crusts and 

phosphorite in the Johnston Atoll EEZ, on Keli Ridge, Black 

Friday Ridge, and several unnamed seamounts. In 1984, the 

U.S. ship S.P. Lee sampled Horizon Guyot and the Johnston 

Island volcanic edifice for crusts and phosphorite. In 1986, 

U.S. and Japanese scientists on the British ship Farnella sampled Karin Ridge and South Johnston Island Ridge for crusts 

and phosphorite. In 1991, a joint United States-Russian cruise 

aboard the Russian ship R.V. Vinogradov also sampled Karin 

Ridge for crusts and phosphorite.

A compilation of chemical data for 103 crust samples collected within the EEZ gives mean cobalt, nickel, and copper 

contents of 0.74, 0.12, and 0.44 percent, respectively. The 

mean cobalt content is among the highest for crusts within 

Pacific EEZs. Crusts in this EEZ have the highest mean titanium and zirconium contents and relatively high cerium and 

tellurium concentrations compared to crust means for other 

EEZs in the Pacific. Johnston Atoll EEZ has one of the best 

potentials for this deposit type among Pacific island EEZs. 

These deposits likely represent an near- to intermediate-term 

resource potential for cobalt, nickel, and possibly other metals. 

Additional exploration work is strongly warranted to further 

delineate the distribution and thickness of high-grade crusts.

Iron-manganese nodules occur on the sediment surface 

of the deep-water abyssal plains to the east of Karin Ridge and 

to the west of Johnston Atoll. Very little work has been done 

on these deposits, and nodule distribution and grade are very 

poorly known. However, GLORIA side-scan sonar images 

(see appendix 2) taken of the sea floor in 1990 indicate that 

nodule coverage may be extensive, in agreement with abundances seen on the few available bottom photographs. Nodules 

farther to the east on the sea floor below international waters 

(Clarion-Clipperton Zone) have been well studied. They 

are abundant and contain high concentrations of copper and 

nickel. In the Central Pacific basin to the southwest, nodules 

are extremely abundant and have intermediate concentrations 

of nickel, copper, and cobalt. If areas of favorable nodule density and favorable grades can be located within the Johnston 

Atoll EEZ, they would offer an intermediate-term resource 

potential.

Phosphorite deposits are widespread on seamounts and 

ridges within the EEZ and occur in the same places as the 

iron-manganese crusts. Phosphorites were sampled during 

many cruises in the Johnston Atoll EEZ (see section on cobaltrich crusts). These deposits are high grade and cover extensive 

areas. Additional exploration is warranted, even though this 

deposit type is likely to have only a long-term resource potential.

Insular phosphorite deposits mined on Johnston Atoll 

in the late 1850s to 1890s and early 1900s were of rather poor 

quality compared to those on Jarvis, Howland, and Baker 

Islands. Extensive modifications made to the islands in support of the U.S. military have further contributed to removal 

of this deposit as a viable resource. The potential for lagoonal 

phosphorites is unknown, because the cores from drilling in 

the lagoon have not been available for scientific study. The 

lagoonal phosphorite resource potential is probably small; 

exploitable insular phosphorite deposits occur within enclosed 

lagoons, whereas Johnston Atoll is an open system. Further 

mining operations in the vicinity of the atoll would conflict 

with military operations and its status as a fish and wildlife 

refuge.

Hydrothermal iron and manganese deposits are likely 

to occur scattered throughout the region, and have been sampled at five location (see fig. 14). This deposit type may have a 

long-term resource potential.

Shallow-water aggregate that can be used for construction consists of sand and gravel composed of coral and shell. 

Extensive construction has occurred on the islands of Johnston 

Atoll using hard-packed coral gravel and cement. Exploration for lagoonal and nearshore sand and gravel may identify 

deposits of this commodity that have immediate economic 

importance for local construction. Defense agencies likely 

possess information on the sand and gravel potential, but those 

documents are not presently available to us.

Shallow- to deep-water precious coral likely occurs 

on seamounts and ridges in the Johnston Atoll EEZ. Bamboo 

coral was collected in many dredges that sampled crusts 

and phosphorite. However, the distribution, abundance, and 
33

resource potential of precious coral are unknown. Shallowwater black coral species typically occur in areas of steep rock 

faces swept by strong currents in water depths greater than 

20 meters. Johnston Atoll appears to have numerous potential 

sites for precious coral. A systematic exploration program is 

needed to delineate this potential resource. If important deposits are found, they would have an immediate economic market.

Summary

Aggregate and precious coral could have an immediate 

economic impact if significant deposits and markets are found. 

Significant cobalt-rich crust deposits occur throughout the 

EEZ, and those deposits may offer a near- to intermediateterm resource potential. Iron-manganese nodules may offer an 

intermediate-term resource potential. The other deposit types 

represent long-term or unknown resource potential. Reconnaissance cruises dedicated to understanding the distribution, 

grade, and tonnage of nodules and additional cruises to define 

the crust resource are recommended.

Selected References

Davis, A.S., Gray, L.B., Clague, D.A., and Hein, J.R., 2002, 

The Line Islands revisited; new 40Ar/39Ar geochronologic 

evidence for episodes of volcanism due to lithospheric 

extension: Geochemistry, Geophysics, Geosystems, v. 3, no. 

3, 10.1029/2001GC000190, 28 p.

Guild, K.M., Lee, M.P., Corvalan, D.J., Dawson, K.M., 

Paidakovich, M.E., Salas, S.J., Piper, D.Z., Swint, T.R., 

Sullivan, L.G., McKelvey, V.E., Mizuno, A., Younse, G.A., 

1984, Mineral-resource map of the circum-Pacific region, 

northeast quadrant: Tulsa, Oklahoma, America Association 

of Petroleum Geologists, Circum-Pacific Map Project, 1 

sheet, 1:10,000,000 scale.

Halbach, P., Manheim, F.T., and Otten, P., 1982, Co-rich 

ferromanganese deposits in the marginal seamount regions 

of the Central Pacific Basin—results of the Midpac ’81: 

Erzmetall, v. 35, p. 447-453.

Halbach, P.E., Sattler, C.D., Teichmann, F., and Wahsner, 

M., 1989, Cobalt-rich and platinum-bearing manganese 

crust deposits on seamounts; nature, formation, and metal 

potential: Marine Mining, v. 8, p. 23-39.

 Hein, J.R., 2002, Cobalt-rich ferromanganese crusts; global 

distribution, composition, origin, and research activities, 

in Polymetallic massive sulphides and cobalt-rich 

ferromanganese crusts; status and prospects: Kingston, 

Jamaica, International Seabed Authority Technical Study 

No. 2, p. 36-89.

Hein, J.R., Manheim, F.T., Schwab, W.C., and Davis, A.S., 

1985, Ferromanganese crusts from Necker Ridge, Horizon 

Guyot, and S.P. Lee Guyot; geological considerations: 

Marine Geology, v. 69, p. 25-54.

Hein, J.R., Manheim, F.T., Schwab, W.C., Davis, A.S., Daniel, 

C.L., Bouse, R.M., Morgenson, L.A., Sliney, R.E., Clague, 

D., Tate, G.B., and Cacchione, D.A., 1985, Geologic 

and geochemical data for seamounts and associated 

ferromanganese crusts in and near the Hawaiian, Johnston 

Island, and Palmyra Island Exclusive Economic Zones: U.S. 

Geological Survey Open-File Report 85-292, 129 p.

Hein, J.R., Bychkov, A.S., and Gibbs, A.E., eds., 1994, Data 

and results from R.V. Aleksandr Vinogradov cruises 91-

AV-19/1, north Pacific hydrochemistry transect; 91-AV19/2, north equatorial Pacific Karin Ridge Fe-Mn crust 

studies; and 91-AV-19/4, northwest Pacific and Bering Sea 

sediment geochemistry and paleoceanographic studies: U.S. 

Geological Survey Open-File Report 94-230, 292 p.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Piper, D.Z., McCoy, F.W., and Swint, T.R., 1985, Manganese 

nodules, sea floor sediment, and sedimentation rates for 

the circum-Pacific region: Tulsa, Oklahoma, America 

Association of Petroleum Geologists, 1 sheet, scale 

1:17,000,000.

 Johnston Atoll
34 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Figure 15. Bathymetric map of the Exclusive Economic Zone (EEZ) of Kingman Reef and Palmyra Atoll (“G” on fig.1); black line shows EEZ 

boundary. Contour interval is 500 meters. The Kiribati EEZ borders the Kingman Reef and Palmyra Atoll EEZ to the southeast.

6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

Kingman

Reef

Palmyra

Atoll

LINE ISLANDS

S.P. LEE

GUYOT

Tabuaeran I.

(Fanning I.)

Teraina I.

(Washington I.)

165o W

165o W

160o W

160o W

5o N 5o N

10o N 10o N

Fe-Mn crust sample sites

Hydrothermal ironstone sample site

Fe-Mn nodule sample sites
35

Kingman Reef and Palmyra Atoll

Land area: 1 km2 (Kingman), 11.9 km2 

 (Palmyra)

EEZ area: 411,600 km2 (see fig. 15); 

 location shown by “G” on 

 figure 1

Political status: Unincorporated territory of the 

United States (Kingman); 

 incorporated territory of the 

 United States, Privately 

 Owned (Palmyra)

Population: Uninhabited 

Island minerals: Aggregate

Island History

Kingman Reef and Palmyra Atoll are located about 

1,713 and 1,778 kilometers south of Honolulu, respectively. 

They are separated by about 61 kilometers.

Kingman Reef was named for Captain W. E. Kingman, 

who discovered it on November 29, 1853, while aboard the 

U.S. ship Shooting Star. He said that it was near the place 

called Danger Rock on some charts and, under that name, it 

was one of the islands claimed by the United States under 

the Guano Act of 1856. However, the reef was first sighted 

by Edmund Fanning in 1798 aboard the U.S. ship Betsy.

The American flag was planted on Kingman Reef on 

May 10, 1922 by Lorrin A. Thurston, who engineered the 

annexation of Hawai’i by the United States, at the request 

of Leslie and Ellen Fullard-Leo, then owners of nearby 

Palmyra Atoll. He took formal possession by reading a 

proclamation of annexation, and leaving a record of the 

proceedings, a certificate of possession, the flag, and copies 

of the Honolulu Advertiser and Star-Bulletin dated May 3, 

1922, all placed at the base of a cairn of coral slabs about 

1.2 meters high. On December 29, 1934, by Executive Order 

of President Franklin D. Roosevelt, Kingman Reef was 

placed under the control and jurisdiction of the U.S. Navy, 

administered from the 14th Naval District. On February 14, 

1941, President Roosevelt issued a second Executive Order 

making Kingman Reef a U.S. national defense area and prohibiting foreign planes and surface craft.

Palmyra Atoll was named on November 7, 1802, for the 

U.S. ship Palmyra commanded by Captain Sawle, but was 

probably first sighted four years earlier by Captain Edmund 

Fanning aboard the American ship Betsy. On the orders of 

King Kamehameha IV, Hawai’i annexed Palmyra in 1862. 

The United States later annexed it along with the Hawaiian 

Islands by the joint resolution of Congress of 1898. Later, 

Congress excluded Palmyra from the Hawaiian boundaries 

in the Hawai’i Statehood Act.

The atoll changed private ownership four times between 

1888 and 1911. In 1911, Judge Henry E. Cooper of Honolulu acquired title to the island and used it for growing 

coconuts. He sold all but two islets to Leslie and Ellen Fullard-Leo in August 1922. When the judge died in 1929, his 

two islets (Home Islands) were passed to his heirs. Until 

2000, ownership of the rest of Palmyra was shared by Fullard-Leo’s three sons, Leslie, Dudley, and Ainsley, who live 

in Hawaii.

During World War II, the U.S. Navy had 600 personnel on the island. The navy dredged a seaplane runway that 

merged the two western lagoons into one, built a causeway 

on the remaining reef, and joined three of the former islets 

into one. They also built an 1,800-meter runway that was 

used by the U.S. Air Force until 1961 but is now unserviceable. It took the Fullard-Leo family many court battles to 

reclaim Palmyra from the military after the war, which 

were finally settled by a Supreme Court decision in 1947. 

In December 2000, the Nature Conservancy purchased Palmyra Atoll for about $30 million from the three Fullard-Leo 

brothers. The following January, the U.S. Fish and Wildlife 

Service approved a National Wildlife Refuge for Palmyra, 

and for Kingman Reef as well.

Geography

Kingman Reef is a low and nearly flat, V-shaped reef 

with a maximum elevation of about 1 meter and a central 

lagoon. It is wet or awash most of the time, so is not usable 

for occupation. At times, the east end is exposed at low 

tide and supports sand cay islands. The V-shaped bit of reef 

remaining is part of a larger atoll that is now mostly submerged. Kingman Reef has an equatorial climate that is hot 

and rainy.

Palmyra Atoll is composed of about 50 islets forming a 

U-shape, surrounded by a barrier reef. There is a lagoon to 

the east of the islets as well as within the central part of the 

U-shape, which is open to the west. The islets are nearly flat 

with a maximum elevation of 2 meters, although trees up 

to about 25 meters tall make them look significantly higher. 

Palmyra Atoll has an equatorial climate that is hot and rainy.

Geologic Setting

The Cretaceous volcanoes that underlie Kingman Reef 

and Palmyra Atoll are part of the Line Islands volcanic chain. 

Three samples from seamounts in or near the EEZ give ages of 

84, 70, and 69 million years. All of the seamounts within the 

EEZ probably have ages within that range of 84 to 69 million 

years. The Kingman-Palmyra EEZ contains about seven large 

seamount complexes and ridges, as well as smaller edifices 

(fig. 15). The remainder of the EEZ consists of sedimentcovered abyssal plain at water depths of about 4,000 to 4,800 

meters. The very large S.P. Lee Guyot (80 by 125 kilometers) 

was sampled on a USGS cruise and found to be about 80 perKingman Reef and Palmyra Atoll
36 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

cent sediment covered on its summit and upper flanks, with 

the remainder coated with rather thin cobalt-rich iron-manganese crusts. Several other seamounts in the EEZ and just 

outside the northern EEZ boundary have also been sampled 

and analyzed.

Offshore Mineral Deposits of Kingman-Palmyra 

Islands

The Kingman-Palmyra EEZ forms a half circle because 

the southeast boundary also forms the northwest EEZ boundary of Kiribati’s Line Islands. Within the Kingman-Palmyra 

EEZ likely occur immediate- to long-term potential mineral 

resources. Mineral deposits within the EEZ are similar to those 

that occur within the Johnston Atoll EEZ, but with greater 

amounts of phosphorite. The following mineral-deposit types 

likely occur in the EEZ:

• Cobalt-rich iron-manganese crusts on seamounts and 

ridges

• Iron-manganese nodules on the deep abyssal plains

• Phosphorite deposits on seamounts and ridges

• Insular and lagoonal phosphorite

• Hydrothermal iron and manganese deposits on sea 

mounts and ridges

• Shallow-water and insular sand and gravel (aggregate)

• Shallow- to deep-water precious coral on seamounts, 

islands, and ridges

Cobalt-rich iron-manganese crusts from S.P. Lee 

Guyot, from several smaller unnamed seamounts, and from 

the flanks of Kingman Reef and Palmyra Atoll, all within the 

Kingman-Palmyra EEZ (fig. 15), were collected and studied 

by USGS and German scientists. In addition, crusts were 

collected from a seamount that lies just outside the northern 

EEZ boundary. Thirty-four samples have been chemically 

analyzed. These crusts have some of the highest cobalt 

concentrations (average 1.2 percent; maximum 2.5 percent) 

measured in samples from the Pacific, as well as high nickel 

(average 0.70 percent), titanium, and cerium contents and 

moderate copper (0.10 percent) and platinum contents. However, the crusts are generally thin because of abundant sediment cover in this equatorial zone of high bioproductivity. It 

is likely that thicker metal-rich crusts will be found on some 

of the seamounts within this EEZ that have not yet been 

sampled; for example, in areas where bottom currents have 

prohibited the accumulation of sediment. These deposits 

represent an intermediate-term resource potential for cobalt, 

nickel, and possibly platinum and other metals. The Kingman-Palmyra EEZ has a significant potential to contain crust 

deposits of high grade and tonnage. It is recommended that 

additional exploration be undertaken.

Iron-manganese nodules occur on the sediment surface of the deep-water abyssal plain to the west of the 

islands. Little work has been done on these deposits, and 

nodule distribution and grade are poorly known. However, 

GLORIA side-scan sonar images taken in 1990 of the sea 

floor indicate that nodule coverage may be extensive. 

Slow sedimentation rates in the abyssal areas support the 

likelihood of extensive nodule coverage, comparable to 

the extremely high nodule coverage immediately to the 

north in the Central Pacific Basin. The dominant sediment is thought to be siliceous ooze, similar to that in the 

nodule province farther to the east in international waters 

(Clarion-Clipperton Zone). There, extensive investigations 

by industry, governments, and academia have established 

that the nodules are abundant and contain high contents of 

copper and nickel. If areas of favorable nodule density and 

grades can be located within the Kingman-Palmyra EEZ, 

then these nodules would offer an intermediate-term potential. It is recommended that the abyssal plain area of the 

EEZ be explored for nodule potential.

Phosphorite deposits are widespread on seamounts 

and ridges within the EEZ and occur in association with 

the iron-manganese crusts. The phosphorite deposits are 

high grade, but the tonnage of the deposits is not known. 

More detailed studies are required to evaluate the resource 

potential of this deposit type in the Kingman-Palmyra 

EEZ, which may offer an intermediate- to long-term 

resource potential.

Insular phosphorite deposits on Kingman Reef and 

Palmyra Atoll are unknown, but the conditions are appropriate for phosphorite to occur. An exploration program for 

insular and lagoonal phosphorites should include drilling on 

the islands and in the lagoons. Discovery of rich phosphorite 

deposits could have an immediate economic impact if the need 

was great enough. However, the recent (2001) placement of 

Kingman Reef and Palmyra Atoll within the National Wildlife 

Refuge system means that any identified resource would not 

be mined except in the case of extreme need.

Hydrothermal iron and manganese deposits are 

likely to occur scattered throughout the region, but as yet 

have only been sampled at one location (see fig. 15). This 

deposit type may have a long-term resource potential.

Shallow-water and insular aggregate for construction on Palmyra consists of sand and gravel composed of 

coral and shell. Construction materials are ubiquitous on 

the atoll, which is predominantly composed of unconsolidated sand, gravel, and reef deposits. Extensive use of construction materials occurred during World War II. The U.S. 

Navy dredged a seaplane runway between middle and eastern lagoons, built causeways on reef flats, and constructed 

a 1.8-kilometer-long runway. Exploration for lagoonal and 

nearshore sand and gravel are likely to identify significant 

deposits that can be used for local construction. Nearshore 

deposits would be limited to the submerged reef terrace 

surrounding the atoll and within the lagoons. In general, 

location of construction materials on this type of island 

is relatively easy. Identifying deposits where exploitation 

will not accelerate land loss or shoreline erosion, nor result 

in permanent habitat loss, is difficult. Armor stone for use 
37

in revetments and shore protection can be mined from the 

reef flat and from beachrock deposits. Because there is no 

significant land mass associated with Kingman Reef, it is 

unlikely that construction materials of economic significance will be identified there.

Shallow- to deep-water precious coral likely occurs 

on seamounts and ridges in the Kingman-Palmyra EEZ. 

Bamboo coral was collected during cruises dedicated 

to the study of iron-manganese crusts. The distribution, 

abundance, and resource potential of precious coral are 

unknown in the Kingman-Palmyra EEZ. Shallow-water 

black coral species typically occur in areas of steep rock 

faces swept by strong currents in water depths greater 

than 20 meters. Kingman-Palmyra has numerous sites 

that fit these criteria. Palmyra has at least three times the 

number of coral species found in Hawai’i and the Caribbean and five times the number found in the Florida Keys. 

It is likely that precious corals will be found among those 

species. A systematic exploration program is needed to 

delineate this potential resource. If important deposits are 

found, they could have an immediate economic market.

Summary

Aggregate, precious coral, and insular and lagoonal 

phosphorite could have an immediate economic market if 

significant deposits are found. Cobalt-rich crusts are high 

grade, but their tonnage is not known. Iron-manganese 

crusts and nodules may offer an intermediate-term resource 

potential. The other deposit types represent long-term or 

unknown resource potentials. Research to determine the 

distribution, grade, and tonnage of the above mentioned 

near- and intermediate-term potential resources is recommended. Research in the area west of Palmyra Atoll will 

be limited because of its past use as an explosives dump 

site. In addition, the designation of Kingman-Palmyra as a 

National Wildlife Refuge will limit activity in the vicinity 

of the island.

Selected References

Davis, A.S., Gray, L.B., Clague, D.A., and Hein, J.R., 2002, 

The Line Islands revisited; new 40Ar/39Ar geochronologic 

evidence for episodes of volcanism due to lithospheric 

extension: Geochemistry, Geophysics, Geosystems, v. 3, no. 

3, 10.1029/2001GC000190, 28 p.

Guild, K.M., Lee, M.P., Corvalan, D.J., Dawson, K.M., 

Paidakovich, M.E., Salas, S.J., Piper, D.Z., Swint, T.R., 

Sullivan, L.G., McKelvey, V.E., Mizuno, A., Younse, G.A., 

1984, Mineral-resource map of the circum-Pacific region, 

northeast quadrant, Tulsa, Oklahoma, America Association 

of Petroleum Geologists, Circum-Pacific Map Project, 1 

sheet, 1:10,000,000 scale.

Halbach, P., Manheim, F.T., and Otten, P., 1982, Co-rich 

ferromanganese deposits in the marginal seamount regions 

of the Central Pacific Basin—results of the Midpac ’81: 

Erzmetall, v. 35, p. 447-453.

Hein, J.R., Manheim, F.T., Schwab, W.C., and Davis, A.S., 

1985, Ferromanganese crusts from Necker Ridge, Horizon 

Guyot, and S.P. Lee Guyot; geological considerations: 

Marine Geology, v. 69, p. 25-54.

Hein, J.R., Manheim, F.T., Schwab, W.C., Davis, A.S., Daniel, 

C.L., Bouse, R.M., Morgenson, L.A., Sliney, R.E., Clague, 

D., Tate, G.B., and Cacchione, D.A., 1985, Geologic 

and geochemical data for seamounts and associated 

ferromanganese crusts in and near the Hawaiian, Johnston 

Island, and Palmyra Island Exclusive Economic Zones: U.S. 

Geological Survey Open-File Report 85-292, 129 p.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Manheim, F.T., and Lane-Bostwick, C.M., 1989, Chemical 

composition of ferromanganese crusts in the world ocean; 

a review and comprehensive database: U.S. Geological 

Survey Open-File Report 89-020.

Kingman Reef and Palmyra Atoll
38 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Figure 16. Bathymetric map of the Exclusive Economic Zone (EEZ) of the Republic of the Marshall Islands (“H” on fig.1); black line shows EEZ 

boundary. Contour interval is 500 meters. The Federated States of Micronesia, Wake Atoll, Kiribati, and Nauru EEZs border the Republic of the 

Marshall Islands EEZ to the west, north, southeast, and south respectively. The Marshallese spellings are used for atoll and seamount names.
39

Republic of the Marshall Islands

Land area: 181 km2 (29 atolls; 5 islands)

EEZ area: 2,131,000 km2 (see fig. 16); 

 location shown by “H” on 

 figure 1

Political status: Independent nation in free 

 association with the United 

 States

Population: 58,800 (2003 estimate)

Island minerals: Insular phosphate/guano 

 deposits; aggregate

Note: The Marshallese spellings are used for atoll and seamount names.

Island History

The Marshall Islands are part of Micronesia, which 

was populated by migrants from the Malaysian-Indonesian 

area thousands of years ago. Several atolls were visited by 

the Spanish in the early and middle 1500s, and the islands 

were subsequently claimed by Spain in l592 but were 

thereafter left more or less alone for nearly 300 years. Germany took over administration of the Marshall Islands in 

l885 and developed trading stations on Jalwoj and Epoon 

Atolls to support a flourishing copra (dried coconut) trade. 

Traditional Marshallese high chiefs (Iroij) ruled under 

indirect colonial German administration.

At the beginning of World War I, Japan took control 

of the Marshall Islands, first under civil and later under 

naval administration. Japan’s headquarters were located 

on Jalwoj Atoll. U.S. military troops took control from 

the Japanese in early l944 following major battles on 

Kuwajleen and Anewetak Atolls. In l947, the United States 

entered into agreement with the U.N. Security Council to 

administer the islands formerly administered by the Japanese. The new agreement was known as Trust Territory of 

the Pacific Islands (TTPI), of which the Marshall Islands 

were a part. The United States undertook nuclear testing 

on Pikinni and Anewetak Atolls from 1946 to 1958, with 

69 test detonations. On May l, l979, the United States recognized the Constitution of the Marshall Islands and the 

establishment of the Government of the Republic of the 

Marshall Islands. After nearly forty years of U.S. administration as a U.N. Trust Territory of the Pacific Islands, 

the Marshall Islands attained independence on October 

21, 1986, under a Compact of Free Association signed by 

President Ronald Reagan on that date. Under the Compact, 

the U.S. will continue use of the Kuwajleen Atoll missile 

test range for at least 30 years.

Geography

Most of the Marshall Islands are atolls with low coral 

limestone and sand islets located between an outer barrier 

reef and a central lagoon. More than 1,200 islets make up the 

atolls. Some of the lagoons are huge. Kuwajleen, which is 

used as a U.S. missile test range, has the largest lagoon (2,174 

square kilometers) in the world and encompasses about 90 

islets. The lagoons of the atolls have maximum water depths 

of about 10 to 100 meters. The highest elevation in the Marshall Islands is about 10 meters, which is located on Likiep 

Atoll. The atolls and islands are situated in two almost parallel 

northwest-southeast chains known as the Ratak (Sunrise) and 

Ralik (Sunset) groups.

Geologic Setting

The Marshall Islands EEZ consists predominantly of huge 

Cretaceous-age volcanic complexes, 34 of which are capped 

by atolls and reefs. However, most are seamounts with summits submerged from about 900 to 2,100 meters below sea 

level. Most of the seamounts are flat-topped guyots. Some of 

the seamounts are capped by submerged reefs, while others are 

capped by carbonate sediment, such as the large Wodejebato 

Guyot. Still others have volcanic rocks exposed at the surface. 

At least 100 small- to medium-size seamounts and 12 huge 

seamounts, or seamount complexes, occur within the EEZ. 

The measured areas of 19 guyots in the EEZ vary from 313 

to 4,776 square kilometers. Conical seamounts are typically 

much smaller. Of 15 that have been measured, all are between 

505 and 793 square kilometers in area. Many seamounts in the 

EEZ have been dated, with ages ranging from 140 to 68 million years. These extinct volcanoes, formed by hot-spot volcanism, delineate at least four separate hot-spot traces.

The five islands in the Marshall Islands that are not atolls 

(Jemo, Majej, Kole, Jebat, Ellep) are low-lying carbonate 

platforms surrounded by fringing reefs. These reef islands are 

probably partly drowned atolls composed of a still emergent 

islet around which a fringing reef developed. The reef and 

limestone caps vary from about 350 to 1,400 meters thick, 

under which is volcanic bedrock.

The remainder of the EEZ is sediment-covered abyssal 

plain, which is located adjacent to the southwest, west, north, 

northeast, and east EEZ boundaries (fig. 16). Nine research 

cruises by U.S., Korean, Japanese, and German ships have 

been carried out within the Marshall Islands EEZ in search of 

cobalt-rich iron-manganese crusts. Phosphorite and bamboo 

coral were also collected incidentally on those research 

cruises. Cobalt-rich crusts are typically much thinner on the 

flanks of atolls than on the summits and flanks of seamounts. 

This is because reef debris from the atolls continually moves 

down the flanks by gravity processes, disturbing the ocean 

floor. The crusts must then begin new growth. Consequently, 

seamounts within the EEZ offer a much greater potential for 

thick crusts than the flanks of atolls.

Republic of the Marshall Islands
40 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Offshore Mineral Deposits of the Marshall 

Islands

The Marshall Islands EEZ is the most extensively 

sampled and studied region in the Pacific Ocean for cobaltrich iron-manganese crusts and seamount phosphorite. It 

has been systematically sampled and studied at many sites 

(see fig. 16). However, other mineral deposit types have not 

been systematically surveyed in the EEZ. A detailed bathymetric map of the Marshall Islands EEZ is available from 

the USGS on the web athttp://geopubs.wr.usgs.gov/map-mf/

mf2324/). The Marshall Islands shares its EEZ boundary 

to the south with Kiribati and Nauru, to the southwest with 

the Federated States of Micronesia, and to the north with 

the U.S. Territory of Wake. Within the EEZ of the Marshall 

Islands occur potential immediate- to long-term mineral 

resources. Mineral deposits that do, or should occur within 

the EEZ include:

• Cobalt-rich iron-manganese crusts on seamounts and 

island flanks

• Iron-manganese nodules on deep abyssal plains

• Phosphorite deposits on seamounts and island flanks

• Insular and lagoonal phosphorite on atolls

• Hydrothermal iron and manganese deposits on sea 

mounts and island flanks

• Shallow-water sand and gravel (aggregate) near and on 

islands

• Shallow- to deep-water precious coral on seamounts 

and island flanks

Cobalt-rich iron-manganese crusts have been extensively studied within the Marshall Islands EEZ. This EEZ contains widespread crust deposits with high contents of cobalt 

and nickel and the highest individual and mean platinum and 

tellurium contents when compared to crusts from other Pacific 

EEZs. Both thickness and grade of crusts on many seamounts 

exceed cut-off levels for potential mining (see appendix 2). 

A compilation of USGS chemical data for 116 crust samples 

from 15 seamounts gives mean cobalt, nickel, and copper 

contents of 0.64, 0.46, and 0.10 percent, respectively, whereas 

a compilation of Japanese data for 310 samples from nine seamounts gives mean cobalt, nickel, and copper contents of 0.73, 

0.58, and 0.11 percent, respectively. In addition, titanium, 

molybdenum, zirconium, and cerium contents are very high in 

the USGS data set.

The thickest crusts occur within saddles in the summit 

region or along summit margin platforms of seamounts. The 

Marshall Islands EEZ has one of the best potentials for this 

resource among the Pacific islands EEZs. These deposits 

represent a near- to intermediate-term resource potential for 

cobalt, nickel, platinum, and possibly other metals. Additional 

exploration in needed to better delineate the locations of thick 

and high-grade crusts, but the greater need is to map in detail 

the small-scale topography of seamounts that have previously 

been the most extensively sampled.

Iron-manganese nodules occur on the sediment surface 

of the deep-water abyssal plains. Very little work has been 

done on these deposits, and nodule distribution and grade are 

poorly known. However, immediately to the east, in the Central Pacific Basin, is a broad area with perhaps the highest documented nodule coverage known. If areas of favorable nodule 

density and favorable grades can be located within the EEZ, 

these nodules would offer an intermediate-term potential.

Phosphorite deposits are widespread on seamounts and 

island flanks within the EEZ and occur in association with the 

iron-manganese crusts. Phosphorites were sampled during all 

the research cruises to the Marshall Islands EEZ. These deposits are high grade and cover extensive areas. Iron-Manganese 

crusts in the EEZ have a higher mean phosphorus content than 

crusts from other EEZs. This relationship should be an indicator of the amount of seamount phosphorite, because the source 

of the phosphorous was the same for both. Additional exploration is recommended, even though this deposit type may only 

have a long-term resource potential.

Insular/lagoonal phosphorite deposits are found on a 

number of Marshall Islands atolls, including Arno, Pikaar, 

Ujlan, Wotto, Ujae, Toke, Epoon, and Kuwajleen, as well as 

on Jemo Island. Samples from Epoon, Pikaar, and Arno Atolls 

average 38.5 percent, 23.7 percent, and 12.6 percent P2

O5, 

respectively. These phosphates are generally thin (<30 centimeters) and occur as a hardpan immediately below a humusrich soil layer in what is called “Jemo soil.” These deposits 

may not be large enough to be of economic importance, but 

they may serve as a local source of fertilizer for farms. The 

lagoons of most Marshall Islands atolls are perhaps too large 

and too deep to host lagoonal phosphorite deposits. The few 

atolls with relatively shallow lagoons, such as Bokak, and the 

reef islands may host insular and lagoonal phosphorite and 

warrant further exploration.

Hydrothermal iron and manganese deposits are likely 

to occur scattered throughout the region and have been sampled at two locations (fig. 16). This deposit type may have a 

long-term resource potential.

Shallow-water and insular aggregate for construction 

consists of sand and gravel composed of coral and shell. Construction materials are ubiquitous on the atolls, which are predominantly composed of unconsolidated sand, gravel, and reef 

deposits. Sand and fine gravel usually occur on the beaches, 

bars, lagoon sand aprons, lagoon floors in general, and the 

unconsolidated parts of islets. Gravel is found on beaches and 

beach ridges seaward of the windward islets and lagoonward 

of the leeward islets, as well as on beaches and ridges along 

channels between islets. Extensive use of construction materials occurs (or has occurred) on many of the atolls, especially 

those with military activities or with large populations centers, such as Majro, Kuwajleen, Anewetak, Pikinni, and Arno 

Atolls. Sand and gravel deposits have been mapped on the 

islets and offshore at these five atolls and are abundant on the 

islets, in the nearshore (<10 meters), and within the deeper 

lagoons. In addition, sand and gravel have been studied on the 

islets of Bokak, Pikaar, Aelok, Lae, Likiep, Toke, Ujae, Ujlan, 
41

Utrok, and Wotto Atolls. Construction has been and continues to be extensive on Majro and Kuwajleen, where local 

sources of aggregate have been used. Reef channels have been 

blasted and dredged, sand aprons and lagoon bottoms dredged, 

islets and reef platforms mined and modified, and piers and 

jetties built. The nuclear tests on Kuwajleen and Anewetak 

produced areas of finer-grained sand sediment than is found 

naturally on the lagoon floors. Exploration for lagoonal and 

nearshore sources of sand and gravel on other atolls is likely 

to identify significant deposits. Armor stone for use in revetments and shore protection can be mined from the reef flat and 

from beachrock deposits, which are common on the Marshall 

Islands atolls and islands. In general, construction materials on 

these types of atolls are abundant, but it is difficult to identify 

deposits where exploitation will not accelerate land loss or 

shoreline erosion, nor result in permanent habitat loss.

Shallow- to deep-water precious coral likely occurs on 

seamounts and island flanks within the Marshall Islands EEZ. 

Bamboo coral was collected in many dredges that sampled 

crusts and phosphorite. It has been estimated that about 68 

of 76 genera of Scleractinia corals that occur in Oceania 

occur in the Marshall Islands EEZ. However, the distribution, abundance, and resource potential of precious corals are 

unknown. Shallow-water black coral species typically occur 

in areas of steep rock faces swept by strong currents in water 

depths greater than 20 meters. Marshall Islands atolls, islands, 

and seamounts have numerous potential sites where precious 

corals should be found. A systematic exploration program is 

needed to delineate this potential resource. If important deposits are found, they could have an immediate economic market.

Summary

Aggregate and precious coral could have an immediate 

economic impact if significant deposits and markets are found. 

Significant cobalt-rich crust deposits occur throughout the 

EEZ, and such crusts, along with iron-manganese nodules, 

may offer a near- to intermediate-term resource potential. The 

other deposit types represent long-term or unknown resource 

potentials. Reconnaissance cruises dedicated to understanding the distribution, grade, and tonnage of precious coral and 

iron-manganese nodules and additional cruises to define the 

crust and phosphorite resources are recommended. Exploratory drilling for insular and lagoon phosphorites is also warranted.

Selected References

Fosberg, F.R., and Carroll, D., 1965, Terrestrial sediments 

and soils of the northern Marshall Islands: Atoll Research 

Bulletin, v. 113, 156 p.

Hein, J.R., 2004, Cobalt-rich ferromanganese crusts; global 

distribution, composition, origin and research activities, 

in Minerals other than polymetallic nodules of the 

International Seabed Area: Kingston, Jamaica, International 

Seabed Authority, Proceedings of a workshop held on 26-30 

June 2000, volume 1, p. 188-256.

Hein, J.R., Schwab, W.C., and Davis, A.S., 1988, Cobaltand platinum-rich ferromanganese crusts and associated 

substrate rocks from the Marshall Islands: Marine Geology, 

v. 78, p. 255-283.

Hein, J.R., Kang, J-K., Schulz, M.S., Park, B-K., 

Kirschenbaum, H., Yoon, S-H., Olson, R.L., Smith, V.K., 

Park, D-W., Riddle, G.O., Quinterno, P.J., Lee, Y-O., Davis, 

A.S., Kim, S.R., Pringle, M.S., Choi, D-L., Pickthorn, L.B., 

Schlanger, S.O., Duennebier, F.K., Bergersen, D.D., and 

Lincoln, J.M., 1990, Geological, geochemical, geophysical, 

and oceanographic data and interpretations of seamounts 

and Co-rich ferromanganese crusts from the Marshall 

Islands, KORDI-USGS R.V. Farnella Cruise F10-89-CP: 

U.S. Geological Survey Open-File Report 90-407, 246 p.

Hein, J.R., Moon, J.-W., Lee, K.-Y., Kim, K.-H., Roberts, L., 

Burrows, M., Park, S.H., Dowling, J., Choi, Y.-J., Zielinski, 

S.E., Chi, S.-B., Benninger, L., Kim, H.-S., and Park, C.-K., 

1998, Composition of Co-rich ferromanganese crusts and 

substrate rocks from the Marshall Islands, Cruise KODOS 

97-4: U.S. Geological Survey Open-File Report 98-375, 71 p.

Hein, J.R., Moon, J.-W., Lee, K.-Y., Dowling, J.S., Kim, 

K.-H., Burrows, M., Park, S.H., Choi, Y.-J., Schuetze, 

A.A., Jung, H.S., Kin, H.-S., Lee, G.C., Park, C.-K., 

Son, S.K., and Park, C.Y., 1999, Co-rich Fe-Mn crusts 

from the Marshall Islands (Leg 1) and hydrothermal and 

hydrogenetic Fe-Mn deposits from Micronesia (Leg 2), 

KODOS 98-3 cruise, West Pacific: U.S. Geological Survey 

Open-File Report 99-412, 63 p.

Hein, J.R., Wong, F.L., and Mosier, D.L., 1999, Bathymetry 

of the Republic of the Marshall Islands and vicinity: U.S. 

Geological Survey Miscellaneous Field Studies Map MF2324, version 1.0, 1 sheet, scale 1: 2,000,000 (and web page

http://geopubs.wr.usgs.gov/map-mf/mf2324/).

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Koppers, A.A.P., 1998, 40Ar/39Ar geochronology and isotope 

geochemistry of the West Pacific Seamount Province: 

Unpublished Ph.D. dissertation, Vrije University, The 

Netherlands, 263 p.

Piper, D.Z., Swint-Ike, T.R., and McCoy, F.W., 1987, 

Distribution of ferromanganese nodules in the Pacific 

Ocean: Chemie der Erde, v. 46, p. 171-184.

Stoddart, D.R., and Scoffin, T.P., 1983, Phosphate rock on 

coral reef islands, in Goudie, A.S., and Pye, K., eds., 

Chemical sediments and geomorphology: London, 

Academic Press, p. 369-400.

Republic of the Marshall Islands
42 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Figure 17. Bathymetric map of the Exclusive Economic Zone (EEZ) of the Federated States of Micronesia (“I” on fig.1); black line shows EEZ 

boundary. Contour interval is 500 meters. The Belau, Guam, and Republic of the Marshall Islands EEZs border the Federated States of Micronesia EEZ to the west-southwest, north, and northeast, respectively.
43

Federated States of Micronesia

Land area: 702 km2 (607 islands)

EEZ area: 2,978,000 km2 (see fig. 17); 

 location shown by “I” on 

 figure 1

Political status: Independent nation in free 

 association with the United

 States

Population: 108,155 (July 2004 estimate)

Island minerals: Phosphate/guano deposits, 

 gold, copper, bauxite, 

 aggregate

Island History

The earliest settlement of greater Micronesia is 

thought to have occurred about 2,000 years ago on the 

western mountainous islands, with immigrants arriving 

from the south. Yap may possibly have been settled even 

earlier, its language suggesting settlers from more varied 

areas, possibly from the west as well. In 1525, Portuguese 

explorers encountered Yap and Ulithi Islands during their 

search for the Spice Islands (Indonesia). Spanish expeditions later made the first European contact with the rest 

of what came to be known as the Caroline Islands. Spain 

claimed sovereignty over the Caroline Islands from 1886 

to 1899. When Spain withdrew from its Pacific insular 

areas, they were sold to Germany, except for Guam, which 

became a U.S. insular area. Germany administered the 

islands from 1899 to 1914, when Japanese naval squadrons 

took military possession of the Marshall, Caroline, and 

Northern Mariana Islands. Japan began its formal administration by a League of Nations mandate in 1920.

The U.N. created the Trust Territory of the Pacific 

Islands (TTPI) in 1947. The Federated States of Micronesia (FSM), along with Palau, the Marshall Islands, and the 

Commonwealth of the Northern Mariana Islands together 

constituted the TTPI. The TTPI came under United States 

Department of the Interior administration in 1951. The 

U.S. President appointed a High Commissioner to administer the Trust Territory, who in turn appointed a district 

administrator for each of the FSM States until 1979. In that 

year, the United States recognized the FSM constitution 

and the establishment of the Government of the FSM at 

both national and state levels. FSM became an independent 

nation in November 1986, at which time the Compact of 

Free Association with the United States was established. 

The Kosrae, Pohnpei (formerly Ponape), Chuuk (formerly 

Truk), and Yap island groups now make up the four states 

of the FSM.

Geography

The 607 islands that constitute the FSM vary from high 

mountainous islands to low-lying coral atolls. Yap is the 

westernmost state, and has a total land area of 118.9 square 

kilometers and lagoon area of 1,049 square kilometers. 

Chuuk consists of seven major island groups, the largest 

being Chuuk proper. It is a complex of 98 islands, 14 of 

which are volcanic, surrounded by a barrier reef enclosing 

2,072 square kilometers of lagoon. Pohnpei is mountainous, 

with 342.4 square kilometers of land area and 769.7 square 

kilometers of lagoon. The impressive ruins at Nan Mandol on 

islets off southeastern Pohnpei date from about A.D. 1200. 

This extensive array of ancient structures was constructed 

from columnar basalt quarried on the main island. Kosrae 

has 111.9 square kilometers of land and no lagoon. More 

than half of the population of approximately 108,000 lives in 

Chuuk State. The cultures are as varied as the geography, and 

eight different languages are spoken.

The major islands of each state are the erosional remnants of long inactive volcanoes, now partially submerged. 

The degree of submergence has determined in part the 

type of reef surrounding the islands. Kosrae has a fringing 

reef with no inner lagoon. The Chuuk group of islands sits 

atop a submerged shield volcano, with a triangular lagoon 

approximately 55 kilometers on a side. Within the lagoon 

are numerous coral and volcanic islands, the latter rising 

as much as 442 meters above sea level, some with fringing 

reefs. The coral islands within the lagoon and at the margins 

of the lagoon rise only about one meter above sea level. The 

Yap islands consist of an elongate, approximately 24-kilometer-long, partially submerged and eroded volcanic edifice, 

encompassed by a fringing- to barrier-reef and lagoon complex. Pohnpei is a high volcanic island that hosts the highest 

peaks in the FSM: Totolom (Dolohmwar) at 791 meters and 

Mt. Nahna Laud at 798 meters.

Gold mineralization occurs in epithermal quartz veins 

and breccia and in hydrothermal iron oxide/silica rocks on 

Maap (also spelled Map) and on the Gagil-Tamil Islands in 

the Yap island group. Gold grades up to about 4 grams per 

ton have been determined. About 4,000 metric tonnes of 

copper ore, averaging 5.2 percent copper, was mined near 

Onean and Gatjapar on Gagil-Tomil Island and at Talangith 

on Maap Island during Japanese occupation. During that 

time, 12,700 metric tonnes of nickel-rich laterite, averaging 

0.7 percent nickel and 44 percent iron, was mined from an 

open pit at Gatjapar.

Geologic Setting

The FSM EEZ can be divided into two broad geologic 

provinces. The first is a complex array of ancient volcanoes 

and ridges that makeup the 2,500-kilometer-long Caroline 

Ridge. The second is a volcanic-arc-subduction zone system 

comprising the Yap Trench, Yap Arc, Philippine Sea backarc area, and the southern margin of the Mariana arc-trench 

Federated States of Micronesia
44 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

system. In addition, among these topographic high areas and 

at the margins of the EEZ occur regions of sediment-covered 

abyssal plain.

The Caroline Ridge can be further divided into eastern, 

central, and western sections that have distinct geologic characteristics. The eastern third of the ridge extends from Kosrae 

Island to Chuuk Atoll and trends northwestward. This segment consists of isolated atolls and seamounts and represents 

the trace of a hot spot that was active between 12 million and 

1 million years ago. The central segment extends westward 

from Chuuk Atoll to Ifalik Atoll-Tarang Bank. This segment 

consists of large carbonate banks and atolls and is generally 

of water depths less than 2,500 meters. The western third of 

Caroline Ridge extends from Ifalik Atoll to the Yap trench 

and trends northwestward. This segment consists of a large 

shallow-water (<2,500 meters) ridge bounded by, and cut 

by, narrow troughs that represent strike-slip faults (southern 

margin), normal faults (northern margin), and small spreading basins. Both the north and south flanks are block faulted. 

The origin of the western two-thirds of Caroline Ridge is not 

certain. That region has been variously interpreted as a relict 

island arc, a leaky transform fault, a leaky transform fault 

combined with a hot-spot trace, and an extinct spreading ridge/

transform fault system. The central and western parts of the 

ridge are about 28 to 24 million years old.

The Yap Arc and Trench represent an Oligocene through 

Neogene (34-1.8 million years old) subduction margin, but one 

that is distinct in many ways from other west and southwest 

Pacific arcs, such as the Mariana Arc. For example, the distance between the arc summit and trench axis is very small and 

subduction may have ended in the late Miocene. Also, many 

of the rocks recovered from the arc (inner trench wall, summit, 

and summit islands) are metamorphic rocks. Many of the volcanic rocks have a compositional signature of oceanic crust and 

thus may be obducted oceanic crust. Rocks dredged from the 

outer trench slope have a mid-ocean ridge basalt (MORB)-like 

composition and are about 7 million years old. Other rocks 

are more typical of volcanic arcs. It has been suggested that 

subduction ended in the late Miocene and that back-arc basin 

crust was obducted onto the volcanic arc. However, these suggestions are difficult to reconcile with the occurrence of hydrothermal mineralization of Quaternary (<1.8 million years old) 

sandstone at the summit of the Yap Arc.

Offshore Mineral Deposits of the FSM

Cobalt-rich iron-manganese crusts were sampled at several sites within the FSM EEZ, and hydrothermal manganese 

within the Yap Arc part of the EEZ, during joint U.S.-Korean 

and Japanese research cruises (fig. 17). Other mineral deposit 

types have not been systematically surveyed in the EEZ. 

Immediate- to long-term potential mineral resources may 

occur within the EEZ of the FSM. Mineral deposits that do, or 

are likely to occur within the EEZ include:

• Cobalt-rich iron-manganese crusts on seamounts and 

ridges

• Iron-manganese nodules on the deep abyssal plains

• Phosphorite deposits on seamounts near the eastern EEZ 

margin

• Insular and lagoonal phosphorite

• Hydrothermal iron and manganese deposits along the 

Yap Arc

• Epithermal gold and base metal deposits along the Yap 

Arc

• Skarn deposits on Caroline Ridge

• Shallow-water sand and gravel (aggregate)

• Shallow- to deep-water precious coral on seamounts, 

ridges, and island flanks

Cobalt-rich iron-manganese crusts have been moderately well studied within the FSM EEZ. This EEZ contains 

widespread crust deposits with moderate contents of cobalt 

(mean 0.40 percent), nickel (0.35 percent), and copper (0.09 

percent) and low platinum contents (0.22 grams per ton). The 

crusts are generally thin, averaging less than 20 millimeters 

on most seamounts sampled. Samples collected from Pali 

seamount (fig. 17) indicate that crusts may be thicker and 

of higher grade on seamounts in the north and northeastern 

sectors of the EEZ. The Pali seamount crusts average 50 millimeters thick, with mean contents of 0.50 percent cobalt, 

0.41 percent nickel, 0.13 percent copper, and 0.30 grams per 

ton platinum. The reason for the generally thin crusts is the 

relatively young age of most of the seamounts and ridges on 

which the crusts grow. The low grades are partly explained 

by the diluting effect of detritus and hydrothermal input from 

the west Pacific volcanic arcs. With the available data, there 

is only a long-term potential for this resource, although the 

northern and northeastern regions of the EEZ should be further 

explored.

Iron-manganese nodules have been tentatively identified 

in a few bottom photographs. Nodules are apparently uncommon, even on the deep abyssal plains of the West Mariana 

Basin and Philippine Sea. It should be noted, however, that no 

research has been carried out in either basin to evaluate nodule 

potential.

Iron-manganese nodules have been recovered from Pali 

seamount (fig. 17). They have relatively small rock nuclei, 

similar to abyssal-plain nodules. The mean cobalt, nickel, and 

copper contents for 10 nodules are 0.43 percent, 0.47 percent, 

and 0.13 percent, respectively. Exploration is required for both 

abyssal-plain and seamount nodules in the FSM EEZ before 

their resource potential can be evaluated.

Phosphorite deposits likely occur on seamounts and 

ridges in the northern and eastern sectors of the EEZ along 

with iron-manganese crusts. Phosphorite has been collected on 

Pali, Olapahd, and Namonuito seamounts and probably occurs 

on other seamounts in those areas. These deposits are likely to 

be high grade and cover extensive areas on seamounts in those 

sectors. Exploration is warranted, even though this deposit 

type offers only a long-term resource potential.

Insular phosphorite was mined from Fais Island (a level 

carbonate platform) in the 1930s during Japanese occupation.
45

About 50,000 tonnes per year with an average grade of 30 

percent P2O5 was mined at the height of operations. A total of 

345,000 tonnes was mined, leaving reserves of about 200,000 

tonnes with a grade of 36 percent P2O5. Phosphate rock has 

also been found and analyzed from Faraulep (23.7 percent 

P2O5), Eauripik (34.8 percent P2O5), and Gafercut (19 percent 

P2O5) Atolls. Reserves on Gafercut are about 11,600 tonnes. 

Phosphorite has been reported to occur on Ngetik Atoll, but 

information about that deposit is scarce. Other phosphate 

deposits may occur in the FSM EEZ on atolls (for example, 

Oroluk, Namonuito, Murito, and Sorol), carbonate platform islands, and shallowly submerged banks (for example, 

Mogami Bank, Gray Feather Bank) that at one time were 

atolls. If high-grade lagoonal phosphate is found, the relatively 

deep lagoons (average 46 meters) would complicate their 

development. Exploration is recommended to delineate the 

potential resource for insular/lagoonal phosphorites.

Hydrothermal iron and manganese deposits have been 

sampled in three dredge hauls from the Yap Arc. Those samples have unusually high nickel (mean 0.48 percent) contents, 

high copper (0.26 percent) and zinc (0.16 percent) contents, 

and typical manganese (44 percent) contents. These deposits 

are likely to be small and widely scattered and have a longterm resource potential. 

Gold and base metals occur in epithermal quartz veins, 

mineralized breccia, and iron/silica deposits in the Yap islands 

group. Two of six dredge hauls collected offshore the areas 

on the islands where gold and base-metal deposits have been 

found recovered vein quartz with enrichments of gold to 

about twice its average concentration in the Earth’s crust. The 

recovery of vein quartz warrants a greater investigation. Location of high-grade deposits would have a short-term resource 

potential.

Samples of a skarn deposit were recovered in a dredge 

haul from Caroline Ridge (9o 10.07’ N latitude; 141o 34.00 E 

longitude). The sample consists predominately of a garnet-rich 

limestone. Ore deposits are commonly associated with such 

deposits on land, and their occurrence in the EEZ of the FSM 

warrants further exploration.

Shallow-water and insular aggregate for construction 

consists of sand and gravel composed of coral and shell. Construction materials are ubiquitous on the reef flats of the volcanic islands, as well as on the atolls and reef islands. Atolls and 

reef islands are composed predominantly of unconsolidated 

sand, gravel, and reef deposits. Sand and fine gravel usually 

occur on the beaches, bars, lagoon sand aprons, lagoon floors 

in general, and the unconsolidated parts of islets. Gravel is 

found on beaches and beach ridges seaward of the windward 

islets and lagoonward of the leeward islets, as well as on 

beaches and ridges along channels between islets. Use of carbonate construction materials occurs on many of the atolls and 

islands. In general, these types of construction materials are 

common on atolls and reef islands, but it is difficult to identify 

deposits where exploitation will not accelerate land loss or 

shoreline erosion, nor result in permanent habitat loss. Armor 

stone for use in revetments and shore protection can be mined 

from the reef flat and from beachrock deposits, which are 

common on the atolls and islands.

On the Yap Islands, building material has been dredged 

from Yunearawey Channel, which separates Maap and GagilTamil Islands, and dredging will likely continue there in the 

future. It has been proposed to dredge Yinbinaew Channel, 

which separates Maap and Rumung Islands, for building materials in the future. Dredging offshore of eastern Gagil near 

Wanyaan is being considered to recover fill for roads. Sand 

dredged from the northern reef flat outside Tamil Harbor is 

being used for the production of concrete. Other sites in the 

Tamil Harbor area have been mined in the past, and those 

near the Meqruur village causeway and near Dugor may be 

mined in the future. Two sites have been dredged off southern 

Yap Island. The site near Ngoof may be occupied again in the 

future. Two dredged sites on northwest Yap Island may again 

be mined in the future, one near Kanif and the other on Faay 

inlet on Miil Channel.

The high volcanic islands have ample volcanic-rock 

aggregate and building stone that provide a higher quality 

material for construction than carbonate sediment. Volcanic 

outcrops on Pohnpei have been studied in some detail and 

have yielded aggregate and building stone. The Pohnpei 

material consists largely of alkali basaltic lavas that are little 

weathered. They have been evaluated for use as coastal riprap 

and armor stone, fluvial hydraulic scour protection, roads and 

pavements, rubble and masonry walls, coastal breakwaters, 

coastal protection structures, and other engineering application. These rocks have good integrity, few fractures, and little 

weathering, making them excellent construction material.

Shallow- to deep-water precious coral likely occurs on 

seamounts and ridges in the FSM EEZ. However, the distribution, abundance, and resource potential of precious coral are 

unknown. Shallow-water black coral species typically occur 

in areas of steep rock faces swept by strong currents in water 

depths greater than 20 meters. The FSM appears to have 

numerous potential sites for this and other precious corals. 

A systematic exploration program is needed to delineate this 

potential resource and to provide background data needed to 

permit its exploitation in an environmentally sound way. If 

important deposits are found, they could have an immediate 

economic market.

Summary

Aggregate, precious coral, and epithermal gold could 

have an immediate economic impact if significant deposits and 

markets are found. Significant iron-manganese crust deposits 

occur throughout the EEZ, but they are generally thin and 

the grades are generally low. Exploration is warranted for 

the northern and eastern sectors of the EEZ, where the thicknesses and grades are likely to be higher. The distribution and 

grade of iron-manganese nodule are unknown. Crusts and 

nodules will likely have a long-term resource potential. The 

other deposit types represent long-term or unknown resource 

potentials. Reconnaissance cruises dedicated to understanding 

Federated States of Micronesia
46 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

the distribution, grade, and tonnage of epithermal base-metal 

deposits, skarn deposits, hydrothermal deposits, and phosphorites are recommended.

Selected References

Burnett, W.C., and Lee, A.I.N., 1980, The phosphate supply 

system in the Pacific region: GeoJournal, v. 4, p. 423-436.

Hawkins, J., and Batiza, R., 1977, Metamorphic rocks of the 

Yap arc-trench system: Earth and Planetary Science Letters, 

v. 37, p. 216-229.

Hein, J.R., 2004, Cobalt-rich ferromanganese crusts; global 

distribution, composition, origin and research activities, 

in Minerals other than polymetallic nodules of the 

International Seabed Area: Kingston, Jamaica, International 

Seabed Authority, Proceedings of a Workshop held on 26-30 

June 2000, volume 1, p. 188-256.

Hein, J.R., Ahn, J-H., Wong, J.C., Kang, J.-K., and others, 

1992, Geology, geophysics, geochemistry, and deep-sea 

mineral deposits, Federated States of Micronesia; KORDIUSGS R.V. Farnella Cruise F11-90-CP: U.S. Geological 

Survey Open-File Report 92-218, 191 p.

Hein, J.R., Koschinsky, A., Halbach, P., Manheim, F.T., 

Bau, M., Kang, J.-K., and Lubick, N., L., 1997, Iron 

and manganese oxide mineralization in the Pacific, in

Nicholson, K., Hein, J.R., Bühn, B., and Dasgupta, S., eds., 

Manganese mineralization; geochemistry and mineralogy 

of terrestrial and marine deposits: Geological Society of 

London Special Publication 119, p. 123-138.

Hein, J.R., Moon, J.-W., Lee, K.-Y., Dowling, J.S., Kim, 

K.-H., Burrows, M., Park, S.H., Choi, Y.-J., Schuetze, 

A.A., Jung, H.S., Kin, H.-S., Lee, G.C., Park, C.-K., 

Son, S.K., and Park, C.Y., 1999, Co-rich Fe-Mn crusts 

from the Marshall Islands (Leg 1) and hydrothermal and 

hydrogenetic Fe-Mn deposits from Micronesia (Leg 2), 

KODOS 98-3 cruise, West Pacific: U.S. Geological Survey 

Open-File Report 99-412, 63 p.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Keating, B.H., Mattey, D.P., Helsley, C.E., Naughton, J.J., 

Epp, D., Lazarewicz, A., and Schwank, D., 1984, Evidence 

for a hot spot origin of the Caroline Islands: Journal of 

Geophysical Research, v. 89, p. 9937-9948.

Mammerickx, J., 1978, Re-evaluation of some geophysical 

observations in the Caroline basins: Geological Society of 

America Bulletin, v. 89, p. 192-196.

Rytuba, R.J., and Miller, W.R., 1990, Geology and 

geochemistry of epithermal precious metal vein systems in 

the intra-oceanic areas of Palau and Yap, western Pacific: 

Journal of Geochemical Exploration, v. 35, p. 413-447.

Stoddart, D.R., and Scoffin, T.P., 1983, Phosphate rock on 

coral reef islands, in Goudie, A.S., and Pye, K., eds., 

Chemical sediments and geomorphology: London, 

Academic Press, p. 369-400.

Usui, A., and Someya, M., 1997, Distribution and composition 

of hydrogenetic and hydrothermal manganese deposits in 

the northwest Pacific, in Nicholson, K., Hein, J.R., Bühn, 

B., and Dasgupta, S., eds., Manganese mineralization; 

geochemistry and mineralogy of terrestrial and marine 

deposits: Geological Society of London Special 

Publication 119, pp. 177-198.
Federated States of Micronesia 47

(Section on Midway Atoll begins on following pages.)
48 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS Fe-Mn crust sample sites

Midway

Atoll

HAWAIIAN RIDGE Pearl / Hermes

Atoll

Kure

Atoll

21o N 21o N

33o N 33o N

177o E 172o W

30o N

180o

177o E 180o 172o W

30o N

Figure 18. Bathymetric map of the Exclusive Economic Zone (EEZ) of Midway Atoll (“J” on fig.1); black line shows EEZ boundary. Contour interval is 500 meters. The Hawaiian EEZ borders the Midway Atoll EEZ to the east.
49

In general, the lagoon is shallow; however, basins as deep 

as 21 m occur in the central part. Several other atolls occur 

near Midway Atoll, including Kure Atoll, 93 kilometers to the 

northwest and the last island in the Hawaiian chain, and Pearl 

and Hermes Reef (Atoll), 167 kilometers to the southeast, 

also part of the Hawaiian chain. The eastern boundary of the 

Midway EEZ is shared with the Hawaiian Islands National 

Wildlife Refuge, which extends from Nihoa Island through 

Pearl and Hermes Atoll.

Geologic Setting

Midway Atoll is part of the 2,500-kilometer-long Hawaiian Ridge, a chain of islands and seamounts extending from 

Kure Atoll at the northwestern end to the island of Hawai’i 

at the southeastern end. The sea-floor topography within the 

central third of the Midway EEZ is characterized by large 

volcanic edifices about 28 million years old built on ocean 

crust about 110 million years old. The oldest volcanic rocks 

recovered from the submerged flanks of Midway are about 

28 million years old, but volcanism occurred intermittently at 

Midway until about 11 million years ago. The volcanic edifice 

underlying Midway Atoll extended above sea level in earliest Miocene time (~24 million years ago). Subsidence carried 

it below sea level, resulting in the development of a shallow 

swamp-like environment that was followed by the introduction of coral and other marine life. Continued subsidence 

culminated in the present coral-atoll structure. The period of 

submergence and coral growth was interrupted several times 

by intervals of emergence. On the basis of two drill cores, the 

top of the extinct basaltic volcano now lies from about 150 

meters below sea level on the south side to 380 meters below 

sea level on the north side.

Deep-water abyssal plains cover most of the northern 

third and southern third of the EEZ. Seamounts are sparsely 

distributed in these areas. 

Offshore Mineral Deposits of Midway Atoll

Within the EEZ of Midway Atoll occur immediate- to 

long-term potential mineral resources. Mineral deposits that 

do, or are likely to occur within the EEZ include:

• Cobalt-rich iron-manganese crusts on volcanic 

edifices

• Iron-manganese nodules on the deep-water 

abyssal plains

• Phosphorite deposits on volcanic edifices

• Insular and lagoonal phosphorite on atolls and 

islands

• Hydrothermal iron and manganese deposits 

on seamounts

• Shallow-water sand and gravel (aggregate) on 

and adjacent to atolls and islands

• Shallow- to deep-water precious coral on sea 

mount island flanks

Midway Atoll

Midway Atoll

Land area: 6.2 km2 (includes Eastern, 

 Sand, and Spit Islets)

EEZ area: 348,004 km2 (see fig. 18); 

 location shown by “J” on

 figure 1

Political status: Unincorporated territory of 

 the United States

Population: 40 U.S. Fish and Wildlife 

 Service personnel (July 2003

 estimate) 

Island minerals: Aggregate, phosphate/guano

Island History

Captain N.C. Middlebrooks (commonly known as Captain 

Brooks) of the Hawaiian Barque Gambia sighted Midway 

Island in 1859 and named it Brooks (Middlebrooks by some 

accounts) Island. Captain William Reynolds of the USS Lackawanna claimed the atoll as a U.S. insular area on August 28, 

1867. This claim was in compliance with instructions from the 

Secretary of the Navy, pursuant to the Guano Act of August 

18, 1856. The Navy renamed it Midway Island because of its 

position on the route between California and Japan. In 1903, 

workers for the Commercial Pacific Cable Company lived on 

Midway, which served as a station for the first trans-Pacific 

cable. From 1935 to 1941, Midway was used as a Pan American China Clipper stopover for Orient-bound flights and for 

the refueling of other flights. The Navy established Midway as 

a Naval Defense Sea Area and Airspace Reservation in 1940, 

a prelude to Midway’s critical role in World War II. It became 

part of the Pacific Airborne Early Warning System in 1957 

and became a Naval Air Station in 1968. In the late 1960s, 

about 3,500 people were living on the island in support of U.S. 

efforts in the Vietnam War. Military facilities were closed in 

stages between September 1993 and 1997. Jurisdiction and 

control of the atoll were transferred to the U.S. Fish and Wildlife Service as part of the National Wildlife Refuge system on 

October 31, 1996, through Executive Order 13022 by President William J. Clinton. Presently, 100 visitors (tourists) are 

allowed on the island at a time. Its current political status is as 

an unincorporated insular area.

Geography

Midway Atoll is about 2,100 kilometers northwest of 

Honolulu, Hawaii. The atoll is 8 to 10.5 kilometers in diameter and consists of two large islets, Sand and Eastern Islands, 

which have a total area of just under 6.2 square kilometers and 

a maximum elevation of 13 meters. Several smaller islets also 

cap the atoll rim. A single reef passage occurs along the south 

rim and several passages are situated along the northwest rim. 
50 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Cobalt-rich iron-manganese crusts have been relatively 

extensively studied within the U.S. EEZ around the entire 

Hawaiian chain of islands. That EEZ contains widespread 

crust deposits with high contents of cobalt and titanium, moderate nickel, and low platinum. The U.S. Minerals Management Service completed an environmental impact statement 

for crust mining in the EEZ of Hawaii. In contrast, a relatively 

small number of samples (25) have been collected from the 

Midway EEZ. Analyses of those samples yield mean cobalt, 

nickel, and copper contents of 0.88 percent, 0.42 percent, and 

0.05 percent, respectively. That mean cobalt content is much 

higher than that of the Hawaiian EEZ (0.69 percent), which is 

based on the analysis of 182 samples. However, the Midway 

EEZ deposits will likely have only an intermediate- to longterm resource potential for cobalt, nickel, and possibly other 

metals, because the seamounts are relatively small and the 

crusts are generally less than 20 mm thick. The National Wildlife Refuge status of much of the region would limit the likelihood of mining as well.

Iron-manganese nodules occur on the sediment surface 

of the deep-water abyssal plain. Little work has been done on 

these deposits, and nodule distribution and grade are poorly 

known. However, GLORIA side-scan sonar images of the sea 

floor indicate that nodule coverage may be extensive. On the 

abyssal plain to the south, outside the EEZ, the average sediment accumulation rate is very slow, which favors extensive 

nodule coverage. If areas of favorable nodule density and 

favorable grades are located within the Midway EEZ, these 

nodules would offer an intermediate-term potential.

Phosphorite deposits are widespread on seamounts and 

ridges within the EEZ and occur in the same places as the 

iron-manganese crusts. These deposits are typically either 

small, high-grade deposits or more widespread, low-grade 

deposits. This deposit type may have a long-term resource 

potential.

Insular phosphorite deposits are known to occur on 

Midway Atoll, which was originally acquired by the United 

States in 1867 under the Guano Act. However, phosphate 

has not been mined from the atoll. Phosphorite likely occurs 

on other atolls, islands, reefs, and banks in the area, because 

conditions are favorable for its formation. The potential for 

lagoonal phosphorite is unknown. A drilling program in 1965 

on Sand Island and in the lagoon showed about 160 to 380 

meters of carbonates and clay resting on basalt, but no phosphorite. An exploration program is needed to delineate this 

potential resource. Again, the National Wildlife Refuge status 

of much of the region limits the likelihood of mining.

Hydrothermal iron and manganese deposits are likely 

to occur scattered throughout the region, but as yet have 

not been sampled. This deposit type may have a long-term 

resource potential.

Shallow-water and insular aggregate for construction 

on Midway is ubiquitous and consists of sand and gravel composed of coral and shell. Local construction materials have 

been used to build two runways and a small harbor. The clearing of two seaplane lanes in the lagoon provided construction 

materials. Nearshore deposits are limited to the submerged 

reef terrace surrounding the atoll and within the lagoon. 

Exploration for lagoonal and nearshore sand and gravel may 

identify deposits that have immediate economic importance 

for local construction. In general, construction materials are 

common on this type of island, but identifying deposits where 

exploitation will not accelerate land loss or shoreline erosion, 

nor result in permanent habitat, loss is more difficult. Armor 

stone for use in revetments and shore protection can be mined 

from the reef flat and beachrock deposits. The military may 

possess data on the sand and gravel potential, but such documents are not presently available to us. 

Shallow- to deep-water precious coral has been discovered and harvested around Midway. About 60 tonnes of 

pink coral has been harvested from the so-called Midway beds 

that occur offshore the northwestern islands of the Hawaiian 

Ridge. These beds were discovered in the mid 1960s and have 

significantly augmented the harvests of pink coral from the 

Mediterranean area and Japan. Precious coral likely occurs on 

other atolls and on seamounts and ridges in the Midway EEZ. 

Shallow-water black coral species typically occur in areas 

of steep rock faces swept by strong currents in water depths 

greater than 20 meters. The lagoon passages and the outer 

flanks of the atoll have potential sites for precious coral. However, its distribution and abundance, and therefore resource 

potential, are unknown. A systematic exploration program 

is needed to delineate this potential resource. If additional 

important deposits are found, they could have an immediate 

economic market.

Summary

Aggregate, precious coral, and insular phosphorite could 

have an immediate economic impact if significant deposits 

are found and an overriding need was identified. Exploitation 

of these commodities would have to address potential environmental and ecological issues. Cobalt-rich crusts have very 

high cobalt contents, but crusts and possibly nodules offer 

only an intermediate- to long-term resource potential. The 

other deposit types represent long-term or unknown resource 

potential. Research cruises dedicated to understanding the distribution, grade, and tonnage of these potential resources are 

recommended.

Selected References

Harper, J.R., 1988, Precious corals prospecting strategies for 

the South Pacific region: CCOP/SOPAC Technical Report 

84, 80 p.

Hein, J.R., 2004, Cobalt-rich ferromanganese crusts; global 

distribution, composition, origin and research activities, 

in Minerals other than polymetallic nodules of the 

International Seabed Area: Kingston, Jamaica, International 

Seabed Authority, Proceedings of a Workshop held on 26-30 

June 2000, v. 1, p. 188-256. 
51

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Ladd, H.S., Tracey, J.I., Jr., and Gross, G.M., 1967, Drilling on 

Midway Atoll, Hawaii: Science, v. 156, p. 1088-1094.

MacDonald, G.A., 1969, Petrology of the basalt cores from 

Midway Atoll: U. S. Geological Survey Professional Paper 

680, p. B1-B10. 

Manheim, F.T., and Lane-Bostwick, C.M., 1989, Chemical 

composition of ferromanganese crusts in the world ocean; 

a review and comprehensive database: U.S. Geological 

Survey Open-File Report 89-020.

Midway Atoll
52 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

10,000

Rota I.

Guam

Maug I.

Agrihan Island

Pagan I.

Guguan I.

Tinian I.

Sarigan I.

Alamagan I.

Anatahan I.

Ascuncion I.

Farallon de Pajaros I.

Farallon de Medinilla I.

SAIPAN I.

PARECE

VELA

BASIN

WES

T

Aguijan I.

140oE 150o E

140oE 150o E

10o N

20o N

Fe-Mn crust sample sites

Hydrothermal vent sites

20o N

10o N

145oE

145oE

Hydrothermal Mn sample sites

Sample sites with both Fe-Mn crusts and hydrothermal Mn

Figure 19. Bathymetric map of the Exclusive Economic Zone (EEZ) of the Commonwealth of the Northern Mariana Islands (“K” on fig.1); black

line shows EEZ boundary. Contour interval is 1,000 meters. The Guam and Japan EEZs border the Commonwealth of the Northern Mariana 

Islands EEZ to the south-southwest and north-northwest, respectively.
53

Northern Mariana Islands

Land area: 477 km2 (14 islands)

EEZ area: 758,121 km2 (see fig. 19); 

 location shown by “K” on 

 figure 1

Political status: Commonwealth in political 

 union with the United States

Population: 78,252 (July 2004 estimate)

Island minerals: Phosphate, aggregate, pozzo- 

 lan

Island History

The Mariana Islands may have been first visited by 

people from Southeast Asia more than 3,500 years ago. The 

inhabitants became known as Chamorro, which included 

descendants of the original immigrants and also those who 

immigrated from the Caroline Islands after trade had been 

established between the two island groups. In 1521, Ferdinand Magellan was the first European to visit the islands, 

specifically Guam and Rota. Spain claimed the islands, 

including Guam, in 1565 and maintained control over them 

for more than 300 years. However, the first permanent Spanish community was not established for about 100 years after 

the islands were appropriated.

Guam was ceded to the United States in 1899 after the 

Spanish-American War and the other islands sold to Germany that same year. In 1914, after the start of World War 

I, Japan exercised control of the Northern Mariana Islands. 

The League of Nations gave control of the islands to Japan 

in 1920. Saipan became the center of Japanese occupation, 

with over 30,000 Japanese residents. The Northern Mariana 

Islands were sites of significant U.S.-Japanese battles during 

World War II. On August 15, 1945, when Japan surrendered, 

the U.S. military took over control of the islands. The Northern Mariana Islands was placed under U.S. administration as 

part of the U.N. Trust Territory of the Pacific Islands (TTPI) 

in 1947. The people of the Northern Mariana Islands decided 

to promote closer links with the United States in the early 

1970s and, as a result, began negotiations for territorial status 

in 1972. A covenant to establish a commonwealth in political 

union with the United States was approved in 1976, and the 

new government and constitution went into effect in January 

1978. The Covenant, which was implemented in its entirety 

in November 1986, conveyed U.S. citizenship for legal 

Commonwealth of the Northern Mariana Islands (CNMI) 

residents. In December 1990, the U.N. Security Council 

terminated the TTPI status for CNMI, FSM States, and the 

Marshall Islands.

Geography

The CNMI comprises 14 islands that delineate a 483-

kilometer-long archipelago (fig. 19). This archipelago sits 

atop the Mariana Ridge, which is about 1,200 kilometers long 

within the CNMI EEZ. Many seamounts occur on the ridge 

between the islands. The southern islands are raised limestone 

platforms that rest on a volcanic edifice, whereas the northern 

islands are entirely volcanic. Six islands have been volcanically active during historic times—Pagan, Agrihan, Asuncion, 

Farallon de Pajaros, Guguan, and Anatahan. In addition, at 

least 12 seamounts along the chain are volcanically or hydrothermally active. The islands of Saipan, Tinian, and Rota, 

located northeast of Guam, share the same geologic history 

with Guam. The CNMI EEZ shares its southern boundary with 

that of Guam and its northern boundary with that of the Japanese Izu-Bonin Arc. The Izu-Bonin volcanic arc is geologically a continuation of the Mariana Arc.

Geologic Setting

The Mariana volcanic arc (also called volcanic ridge or 

island arc) is part of a subduction system in which the Pacific 

Plate plunges beneath the Philippine Sea Plate and into the 

Earth’s mantle along the Mariana Trench (see figs. 2, 19). The 

volcanic chain of seamounts and islands is located about 200 

kilometers west of the trench axis. The Mariana Arc started to 

develop about 40 million years ago, and volcanic activity has 

occurred at various places along the arc since that time.

West of the Guam-Mariana Arc is the mostly sedimentcovered floor of the Philippine Sea (a back-arc basin), with 

numerous seamounts, ridges, and basins that are less than 

20 million years old. The basins and ridges consist of (1) the 

Mariana Trough, an active back-arc spreading center located 

immediately west of the Mariana Arc, (2) The West Mariana 

Ridge, a remnant (extinct) volcanic arc, and (3) the Parece 

Vela Basin abyssal plain (fig. 19).

The Mariana Trench is partly filled by sediment. Many serpentine diapirs and mud volcanoes occur in the region between 

the trench axis and the volcanic arc. East of the trench is the 

sediment-covered Pacific Ocean abyssal plain. At least ten large 

Cretaceous (>65 million years old) seamounts protrude through 

the abyssal plain sediment within the CNMI EEZ. These seamounts were constructed on the oldest part of the Pacific Ocean 

crust, which is Jurassic in age (>142 million years old).

In summary, the CNMI EEZ encompasses a variety of 

geologic, morphologic, and tectonic environments. These 

include, from east to west, (1) Cretaceous-age seamounts on 

the Pacific Plate abyssal plain, which includes the Magellan 

Seamount Province, (2) deep Mariana Trench, (3) volcanically active Mariana Arc upon which the islands of the CNMI 

are located, (4) Mariana Trough, a back-arc basin spreading 

center, (5) West Mariana Ridge, a remnant arc, and (6) Parece 

Vela Basin, an abandoned Tertiary back-arc basin.

Offshore Mineral Deposits of the Northern 

Mariana Islands

Within the EEZ of the CNMI occur near- to long-term 

potential mineral resources. Mineral deposits that do, or are 

Northern Mariana Islands
54 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

likely to occur within the EEZ include:

• Cobalt-rich iron-manganese crusts on Cretaceous sea 

mounts

• Iron-manganese nodules

• Phosphorite deposits on Cretaceous seamounts

• Epithermal gold deposits along the active volcanic arc

• Hydrothermal manganese and iron oxide deposits along 

the active arc and back-arc

• Hydrothermal polymetallic sulfides and gold along the 

active arc and back-arc

• Insular and lagoonal phosphorite deposits

• Shallow-water sand and gravel deposits near the islands

• Shallow- and deep-water precious coral on island flanks 

and seamounts

Cobalt-rich iron-manganese crusts occur on the seamounts located east of the Mariana Trench. The distribution 

and morphology of the seamounts in that region are poorly 

known. The distribution, grade, and tonnage of metal-rich 

crusts on those seamounts are also poorly known, because 

no research cruise has been dedicated to their study. Data 

for crusts from nearby seamounts indicate that crusts on seamounts within that sector of the CNMI EEZ have an excellent potential to be thick and have high contents of cobalt, 

nickel, and platinum. It is recommended that these seamounts be explored for their mineral potential. These crust 

deposits represent an intermediate-term resource potential for 

cobalt, nickel, platinum, and perhaps other metals.

Crusts also occur on volcanic rocks that make up the 

West Mariana Ridge. Those crusts are likely to be thin, 

because of the relatively young age of the substrate, and 

of relatively low grade, because of dilution by detrital and 

hydrothermal minerals. These crusts would have a long-term 

resource potential.

Iron-manganese nodules have seldom been recovered 

from the abyssal-plain surface to the east of the Mariana 

Trench. Nodules have been recovered at depth in sediment 

cores, indicating that the current high rates of sedimentation 

do not favor nodule occurrence on the sea floor. However, 

bottom photographs reveal a few areas where nodules do 

occur. If areas of favorable nodule density and grade can be 

located within the CNMI EEZ, the deposits may offer an 

intermediate- to long-term resource potential. In the areas of 

the Mariana Trough, West Mariana Ridge, and Parece Vela 

Basin, nodules are even less likely to be present, again owing 

to high sediment accumulation rates.

Phosphorite deposits occur on the Cretaceous seamounts with iron-manganese crusts, and their distribution 

and grade are also poorly known. These deposits are typically either small, high-grade deposits or more widespread, 

low-grade deposits. This deposit type probably has a longterm resource potential.

Gold deposits of epithermal origin are known to occur 

on islands along the Yap and Belau volcanic arcs to the 

south and probably also occur offshore along the intersection of faults and fracture zones and in submerged calderas. 

Epithermal gold has not been found in the CNMI EEZ, but 

geologic considerations indicate that it may occur along 

the Mariana Arc in submerged calderas (such as Maug and 

Esmeralda Bank) and in areas of back-arc spreading, such 

as the Mariana Trough. Recent work along the Mariana Arc 

supports these speculations. If high-grade gold deposits do 

occur offshore, they would offer a near- to intermediate-term 

resource.

Manganese oxides of hydrothermal origin are known to 

occur extensively along the Mariana, Yap, and Palau volcanic arcs. From analysis of 26 samples from the Mariana Arc, 

manganese averages 47 percent and zinc 0.26 percent. Manganese oxides cement sandstone and form layers within the 

sediments. In places the manganese deposits have high contents of molybdenum, nickel, zinc, and/or chromium. However, because large deposits of most of these metals occur 

on the continents, they offer only an intermediate- to longterm resource potential. It may be found that other metals of 

greater economic importance are enriched in the manganese 

oxide deposits in volcanic arcs; chromium-rich deposits 

along the Yap Arc were only discovered in 1991. The backarc hydrothermal manganese deposits have not been studied 

in detail, and their resource potential is unknown but probably represents a long-term resource.

Polymetallic sulfides, sulfates, and sulfur of hydrothermal origin have been found within the CNMI EEZ at 

four submarine sites along the Mariana Arc and at three sites 

along the eastern margin of the Mariana Trough spreading 

center (see fig. 19). Sulfides have not been found in Maug 

Caldera on the Mariana Arc, but hydrothermal activity has 

been documented there and hydrothermal iron oxides and 

iron carbonates have been found, indicating that hydrothermal sulfides are also likely to be present. In addition, 

hydrothermal activity has been found at seven additional 

sites along the Mariana Arc; those sites have not yet been 

explored for polymetallic sulfide deposits. Most of these 

discoveries are new, and the compositions of the deposits 

are not yet available. Volcanic-arc and back-arc polymetallic 

sulfides are commonly rich in gold and silver, with variable 

amounts of zinc, lead, and copper. For example, sulfides 

from the Okinawa Trough back-arc basin have very high 

gold and silver contents, as do the deposits in the Mariana 

Trough. There is a good potential to find large, high-grade 

polymetallic sulfide deposits along the active Mariana Arc 

and back-arc basin. If gold- and silver-rich polymetallic 

sulfides are found within the CNMI EEZ, they would have a 

short- to intermediate-term resource potential.

Insular phosphorites averaging 20 to 26 percent P2

O5

occur on Saipan, Rota, Tinian, and Aguijan Islands. During 

Japanese occupation of the islands, phosphate mining began 

on Rota in 1937 and on Saipan in 1938 and continued until 

the United States took control of the islands in 1944. During 

those few years, 236,000 metric tonnes of ore was mined from 

Rota and 88,000 from Saipan. Rota may contain as much as 

300,000 tonnes of reserves and Tinian hosts about 30,000 

tonnes of reserves, both at about 23 percent P2

O5. The reserves 
55

on Saipan and Aguijan are unknown. An exploration program 

to identify additional reserves is warranted. Lagoonal phosphate is not known to occur in the Mariana Islands.

Sand and gravel deposits occur in shallow water adjacent to much of the coastline of Saipan, Rota, and Tinian 

Islands. Rota and Tinian have narrow fringing reefs with 

pocket sand beaches. Although some offshore sand and 

gravel deposits exist at Rota, exploitation of these deposits 

and of the beach sands will have to consider environmental 

issues. Tinian has potentially exploitable sand and gravel 

deposits off Kammar Beach and probably off Invasion 

Beach. However, production of aggregate should presently 

be limited to the adequate on-island quarries because of environmental issues related to nearshore and beach mining; in 

addition, abandoned offshore military dump sites and marine 

sanctuaries warrant additional caution for offshore mining. 

Western Saipan has a wide barrier reef with good back-reef 

potential for sand and gravel. Limiting factors would include 

the resort on Mañagaha Island and erosion problems on 

Saipan. The rest of Saipan has a narrow fringing reef and 

small pocket beaches. Exploitation for building aggregate of 

numerous on-land limestone and volcanic rock outcrops in 

relatively remote areas would be the most environmentally 

sound approach. Fluvial aggregate and beach-placer deposits 

are limited in the CNMI. Aggregate offshore western Saipan 

offers a near-term resource potential and could be mined if 

environmental issues are addressed.

Precious coral is found in shallow to deep water at 

many places around the islands in the CNMI EEZ. A systematic exploration program is needed before exploitation of this 

resource can proceed in a controlled and informed manner. 

Precious coral has an immediate economic market if significant occurrences are found, but resource renewal rates must 

be maintained.

Summary

Sand and gravel and precious coral have immediate economic markets. Insular phosphorite and perhaps epithermal 

or hydrothermal gold- and silver-rich polymetallic sulfide 

deposits could have a near-term resource potential. Cobalt-rich 

crusts, iron-manganese nodules, and base-metal polymetallic sulfide deposits may offer an intermediate-term resource 

potential. The other deposit types may represent long-term 

potential resources that cannot be evaluated without additional 

information. Cruises are recommended to determine the distributions, grades, and tonnages of these deposits. In addition, 

available bathymetric maps of the CNMI EEZ are not good 

enough for exploration, except for a narrow swath along the 

volcanically active arc. Much of the CNMI EEZ should be 

mapped by multi-beam bathymetric and sidescan sonar techniques.

Selected References

Embley, R.W., Baker, E.T., Chadwick, W.W., Jr., Lupton, 

J.E., Resing, J.A., Massoth, G,J., and Nakamura, K., 

2004, Explorations of Mariana arc volcanoes reveal new 

hydrothermal systems: EOS, Transactions of the American 

Geophysical Union, v. 84, no. 4, p. 37, 40. 

 Hein, J.R., 2004, Cobalt-rich ferromanganese crusts; global 

distribution, composition, origin and research activities, in

Minerals other than polymetallic nodules of the International 

Seabed Area: Kingston, Jamaica, International Seabed 

Authority, Proceedings of a workshop held on 26-30 June 

2000, v. 1, p. 188-256.

Hein, J.R., Fleishman, C.L., Morgenson, L.A., Bloomer, S.H., 

and Stern, R.J., 1987, Submarine ferromanganese deposits 

from the Mariana and Volcano volcanic arcs, West Pacific: 

U.S. Geological Survey Open-File Report 87-281, 67 p.

Hein, J.R., Moon, J.-W., Lee, K.-Y., Dowling, J.S., Kim, K.-H., 

Burrows, M., Park, S.H., Choi, Y.-J., Schuetze, A.A., Jung, 

H.S., Kin, H.-S., Lee, G.C., Park, C.-K., Son, S.K., and Park, 

C.Y., 1999, Co-rich Fe-Mn crusts from the Marshall Islands 

(Leg 1) and hydrothermal and hydrogenetic Fe-Mn deposits 

from Micronesia (Leg 2), KODOS 98-3 cruise, West Pacific: 

U.S. Geological Survey Open-File Report 99-412, 63 p.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, J.-

K., and Roberts, L., 2000, Cobalt-rich ferromanganese crusts 

in the Pacific, in Cronan, D.S., ed., Handbook of marine 

mineral deposits: Boca Raton, Florida, CRC Press, p. 239-

279.

National Oceanic and Atmospheric Administration, Submarine 

ring of fire 20004—Mariana Arc, at http://oceanexplorer.

noaa.gov/explorations/04fire/welcome.html, accessed 

September 2005.

Rodgers, J., 1948, Phosphate deposits of the former Japanese 

Islands in the Pacific; a reconnaissance report: Economic 

Geology, v. 43, p. 400-407.

Schulz, M.S., and Hein, J.R., 1991, Petrography and chemistry 

of hydrothermal manganese oxyhydroxides from the Mariana 

and Izu-Bonin Volcanic arcs, West Pacific: U.S. Geological 

Survey Open-File Report 91-557, 80 p.

Stüben, D., Bloomer, S.H., Taïbi, N.E., Neumann, Th., Bendel, 

V., Püschel, U., Barone, A., Lange, A., Wu, S., Li, C., and 

Zhang, D., 1992, First results of study of sulphur-rich 

hydrothermal activity from an island-arc environment; 

Esmeralda Bank in the Mariana Arc: Marine Geology, v. 103, 

p. 521-528.

Usui, A., and Someya, M., 1997, Distribution and composition 

of hydrogenetic and hydrothermal manganese deposits in the 

northwest Pacific, in Nicholson, K., Hein, J.R., Bühn, B., and 

Dasgupta, S., eds., Manganese mineralization; geochemistry 

and mineralogy of terrestrial and marine deposits: Geological 

Society of London Special Publication 119, p. 177-198.

Northern Mariana Islands
56 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

6,000 5,000 4,000 3,000 2,000 1,000 0

DEPTH, IN METERS

Wake

Atoll

160n E

25n N

172n E

15n N

160n E 172n E

25n N

15n N

Figure 20. Bathymetric map of the Exclusive Economic Zone (EEZ) of Wake Atoll (“L” on fig.1); black line shows EEZ boundary. Contour interval 

is 500 meters. The Republic of the Marshall Islands EEZ borders the Wake Atoll EEZ to the south-southeast.
57

Wake Atoll

Land area: 6.5 km2

EEZ area: 406,307 km 2 (see fig. 20); location 

shown by “L” on figure 1

Political status: Territory of the United States

Population: 200 (July 2003 estimate)

Island minerals: Aggregate

Island History

The great distances that separate Wake Atoll from the 

northern Marshall Islands and from other islands in the region, 

and its barren nature, suggest that Wake Atoll may never have 

been permanently inhabited by the migrants from the Malaysian-Indonesian region that settled the Marshall Islands to the 

south thousands of years ago. There have been no reports of 

artifacts from that wave of migrations. Wake was discovered 

by Captain William Wake of the British schooner Prince William Henry in 1796, although there are claims that it was visited by Europeans as early as 1568. The position of Wake was 

determined in December 1841 by Charles Wilkes, leader of a 

U.S. exploring expedition. The two smaller of the three islets 

on Wake Atoll were named in honor of Wilkes and the artist 

Titian Peale on the same cruise by A. Wetmore of the USS 

Tanager expedition in July 1923. The U.S. flag was raised 

on Wake in 1898 by General F.V. Green from the SS China

and again by General Merritt from the U.S. Army Transport 

Thomas.

The United States formally annexed Wake under President William McKinley on 17 January 1899 in a ceremony 

on Wake conducted by Commander E.D. Taussig of the USS 

Bennington. The 1923 Tanager expedition mapped Wake Atoll 

and cataloged its biota. The U.S. Navy took over jurisdiction 

of Wake in 1935 by Executive Order. Pan American Airways 

constructed an airport during that same year. President F.D. 

Roosevelt made Wake a National Defense area in February1941, and it was a naval and air base from 1939 to 1941. 

Wake was occupied by Japanese forces during World War II 

after the bombing of Pearl Harbor. Wake was then transferred 

back to the United States in surrender documents and reoccupied by the United States in September 1945. President 

J.F. Kennedy, by Executive Order No. 11048 on 5 September 

1962, made the Secretary of the Interior responsible for the 

civil administration of the atoll. The order vested in the Secretary all executive and legislative authority necessary for that 

administration and all judicial authority other than the authority of the U.S. District Court for the District of Hawai’i. The 

Congress later extended the jurisdiction of the U.S. District 

Court for the District of Hawai’i to all civil and criminal cases 

arising on or within Wake Atoll. Since 1 October 1994, the 

Ballistic Missile Defense Organization (within the Office of 

the Secretary of Defense) has funded administration on Wake, 

which the U.S. Army Space and Strategic Defense Command 

carries out under a use permit. The atoll has approximately 

200 inhabitants, all contract personnel.

Geography

Wake Atoll is about 3,714 kilometers west of Honolulu 

and 2,426 kilometers northeast of Guam. Wake Atoll measures 

about 7.8 by 3.3 kilometers and consists of three islets, Wake, 

Peale, and Wilkes, leaving only the northwest rim without 

continuously emergent land. Causeways connect these three 

islets. The highest and average elevations are 6.4 and 3.7 

meters above sea level, respectively. Each of the three islets 

has a point that is near the maximum elevation. Beaches along 

most of the coast of the three islets are very wide, averaging 

about 90 meters. The shallow lagoon has a maximum depth of 

about 4.5 meters and is completely enclosed by the atoll reef 

rim except for a single artificial channel on the southwest side 

that separates Wilkes and Wake islets. The lagoon is generally less than 1 meter deep in its southeast quadrant, where 

most development is located. No drilling or seismic studies, 

to our knowledge, have been attempted on Wake to establish 

the thickness of the coral cap resting on the underlying Cretaceous-age volcanic structure, the nature of the contact between 

the two, nor the possible presence at depth of any mineral 

resource.

Geologic Setting

Many large to small seamounts formed along the Southern Wake seamount hot-spot trail from 120 to 97 million years 

ago (Cretaceous). Some of those volcanoes showed volcanic 

rejuvenation later in the Cretaceous, about 90 to 85 million 

years ago. Seamounts within the Wake Atoll EEZ, including 

the edifice on which Wake Atoll sits, likely fall within that age 

range, although only one seamount in the EEZ has been dated. 

A sediment-covered abyssal plain ranging in water depth from 

about 5,200 to 5,800 meters surrounds these seamounts.

Offshore Mineral Deposits of Wake Atoll

The southern EEZ boundary is shared with that of the 

Republic of the Marshall Islands. Short- to long-term potential mineral resources likely occur within the EEZ of Wake 

Atoll, although their grades, tonnages, and distributions are 

unknown. Most of our conclusions are based on inferences 

from the geologic setting and information from surrounding 

areas, especially the Marshall Islands. Mineral deposits within 

the EEZ may include:

• Cobalt-rich iron-manganese crusts on sea 

mounts

• Iron-manganese nodules on the abyssal plain

• Phosphorite deposits on seamounts

Wake Atoll
58 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

• Hydrothermal iron and manganese deposits on seamounts 

• Insular/lagoonal phosphorite on Wake Atoll

• Shallow-water sand and gravel (aggregate) on 

and adjacent to Wake Atoll

• Shallow- to deep-water precious coral on sea 

mount and island flanks

Cobalt-rich iron-manganese crusts have not been studied within the Wake Atoll EEZ. However, extensive work has 

been done in the Marshall Islands to the south by the USGS 

and by government agencies of Korea and Japan. Extensive 

proprietary work by Japanese agencies has also taken place in 

adjacent international waters. All data indicate that thick crusts 

rich in cobalt, nickel, and platinum should occur on seamounts 

within the Wake EEZ. Work done by the USGS in cooperation 

with the Korea Ocean Research and Development Institute 

to the south in the Marshall Islands EEZ and with Scripps 

Institute of Oceanography in international waters to the west 

of the Wake EEZ show that the crusts are more enriched in 

platinum than those in all other Pacific areas. Mean cobalt, 

copper, nickel, and platinum contents for 20 crust samples collected near the Wake EEZ are 0.64 percent, 0.48 percent, 0.13 

percent, and 0.6 grams per ton, respectively. The Wake EEZ 

crusts may likewise contain high metal concentrations. The 

extent of development of crust deposits with high metal contents is unknown, but the large number and size of seamounts 

in the EEZ indicate that an intermediate-term resource potential may occur for cobalt, nickel, and possibly platinum and 

other metals. It is recommended that an exploration program 

for crusts be carried out in the Wake EEZ.

Iron-manganese nodules appear to be common on the 

few bottom photographs taken of the sediment surface in the 

deep-water abyssal plain that surrounds the seamounts in the 

Wake EEZ. Little work has been done on these deposits, and 

nodule distribution and grade are poorly known. The few 

bottom photographic stations scattered throughout the vast 

region of the North Pacific Ocean suggest that nodule coverage is locally high and possibly high over large areas. Proprietary work by Japanese scientists in nearby areas also indicates 

extensive nodule coverage and high copper and nickel contents. The low sediment accumulation rates in the area also 

favor nodule growth. If areas of favorable nodule coverage 

and grades can be located within the Wake EEZ, these nodules 

would offer an intermediate-term potential resource.

Phosphorite deposits on seamounts within the Wake 

EEZ have not been sampled. However, samples taken from 

adjacent areas indicate that phosphorite might be widespread 

on seamounts in the Wake EEZ. These deposits are typically either small, high-grade deposits or more widespread, 

low-grade deposits. This deposit type may have a long-term 

resource potential.

Insular phosphorite deposits are not known to occur on 

Wake Atoll, but all the conditions are appropriate for them to 

have formed, especially within the enclosed lagoon. An exploration program should include sampling of islet outcrops and a 

drilling program on the islets and in the lagoon. Some data and 

samples may already exist from construction projects undertaken in support of military activities. There would be a nearterm resource potential if a suitable deposit were found.

Hydrothermal iron and manganese deposits are likely 

to occur scattered throughout the region, but as yet have 

not been sampled. This deposit type may have a long-term 

resource potential.

Shallow-water and insular aggregate for construction uses on Wake consists of sand and gravel composed of 

coral and shell. Construction materials are ubiquitous on the 

atoll, which is composed predominantly of unconsolidated 

sand, gravel, and reef deposits. Extensive use of construction materials has occurred, including the building of a single 

large runway and a small harbor. Nearshore deposits are limited to the submerged reef terrace surrounding the atoll and 

areas within the lagoon. In general, construction materials are 

common on this type of island, but identifying deposits where 

exploitation will not accelerate land loss or shoreline erosion, 

nor result in permanent habitat loss, is difficult. Armor stone 

for use in revetments and shore protection can be mined from 

the reef flat and beachrock deposits. Exploration for lagoonal 

and nearshore sand and gravel may identify deposits that have 

immediate economic importance. The military likely possesses information on the sand and gravel potential, but such 

documents are not presently available to us.

Shallow- to deep-water precious coral likely occurs on 

seamounts and island flanks within the Wake EEZ. Its distribution, abundance, and resource potential are unknown, and 

a systematic exploration program is needed to delineate this 

potential resource. If important deposits are found, they would 

have an immediate economic market.

Summary

Aggregate, precious coral, and insular phosphorite could 

have an immediate economic impact if significant deposits 

and markets are found. Exploitation of these commodities 

would have to address environmental and ecological issues. 

Cobalt-rich crusts and iron-manganese nodules may offer an 

intermediate-term resource potential. The other deposit types 

represent long-term or unknown resource potential. Without 

detailed data, it is difficult to assess the resources of these mineral deposit types within the EEZ. Research cruises dedicated 

to understanding the distribution, grade, and tonnage of these 

potential resources are recommended.

Selected References

Hein, J.R., 2004, Cobalt-rich ferromanganese crusts; global 

distribution, composition, origin and research activities, 

in Minerals other than polymetallic nodules of the International Seabed Area: Kingston, Jamaica, International 

Seabed Authority, Proceedings of a workshop held on 26-

30 June 2000, v. 1, p. 188-256.

Hein, J.R., Kang, J-K., Schulz, M.S., Park, B-K., Kirschen-
59

baum, H., Yoon, S-H., Olson, R.L., Smith, V.K., Park, 

D-W., Riddle, G.O., Quinterno, P.J., Lee, Y-O., Davis, 

A.S., Kim, S.R., Pringle, M.S., Choi, D-L., Pickthorn, 

L.B., Schlanger, S.O., Duennebier, F.K., Bergersen, D.D., 

and Lincoln, J.M., 1990, Geological, geochemical, geophysical, and oceanographic data and interpretations of 

seamounts and Co-rich ferromanganese crusts from the 

Marshall Islands, KORDI-USGS R.V. Farnella Cruise 

F10-89-CP: U.S. Geological Survey Open-File Report 90-

407, 246pp.

Hein, J.R., Koschinsky, A., Bau, M., Manheim, F.T., Kang, 

J.-K., and Roberts, L., 2000, Cobalt-rich ferromanganese 

crusts in the Pacific, in Cronan, D.S., ed., Handbook of 

marine mineral deposits: Boca Raton, Florida, CRC Press, 

p. 239-279.

Hein, J.R., Zielinski, S.E., Staudigel, H., Chang, S.-W., 

Greene, M., and Pringle, M.S., 1997, Composition of Corich ferromanganese crusts and substrate rocks from the 

NW Marshall Islands and international waters to the north, 

Tunes 6 cruise: U.S. Geological Survey Open-File Report 

97-482, 65 p.

Koppers, A.A.P., 1998, 40Ar/39Ar geochronology and isotope 

geochemistry of the West Pacific Seamount Province: The 

Netherlands, Vrije University, unpublished Ph.D. dissertation, 263 p.

Piper, D.Z., Swint-Ike, T.R., and McCoy, F.W., 1987, Distribution of ferromanganese nodules in the Pacific Ocean: 

Chemie der Erde, v. 46, p. 171-184.

Wake Atoll
60 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Conclusions

Little information is available on which to base a resource 

assessment for minerals that may occur within the EEZs of 

the twelve islands or island groups considered here. Exploitable shallow-water and insular sand and gravel deposits occur 

within each of the twelve EEZs. These deposits are readily 

available and have been or can be developed. The main challenge for their exploitation is to proceed in an environmentally 

sound way. Shallow- and deep-water precious corals are likely 

to occur in each EEZ, but it is not known if they occur with 

the quality and tonnage required for large-scale exploitation. 

Precious coral has been exploited with small-scale operations 

in several of the EEZs. The main concern is exploiting precious coral to an extent that it cannot recover. Precious coral is 

the only potentially renewable resource considered here.

Each of the twelve EEZs has a high likelihood for the 

occurrence of an exploitable resource for one of the three main 

deep-ocean mineral-deposit types: cobalt-rich iron-manganese 

crusts, iron-manganese nodules, and polymetallic sulfides (see 

fig. 21). This likelihood is based on the geologic and oceanographic settings, as well as the size of the area available in 

which a particular deposit type can form. American Samoa, 

Howland-Baker Islands, and Jarvis Island are more likely 

to contain nodule deposits, whereas the Northern Mariana 

Islands, Guam, and Belau are more likely to contain polymetallic sulfide deposits. The remainder of the EEZs are likely to 

contain cobalt-rich crust deposits as the dominant deep-water 

deposit type. The Marshall Islands EEZ has been explored 

to a far greater extent than any other, with cobalt-rich crusts 

as the main focus. However, even with that relatively intense 

activity, data are too few to make a robust resource analysis. 

Each new research cruise to these EEZs brings new discoveries that contribute to our fundamental understanding of their 

potential mineral resources. An excellent example is the recent 

(2004) U.S. NOAA cruise to the CNMI that made many new 

resource-applicable discoveries (http://oceanexplorer.noaa.

gov/explorations/04fire/welcome.html). The clear and fundamental message from our analysis is that the data required 

to make resource assessments for the Pacific EEZs of U.S. 

affiliation are not yet available. A national program should be 

developed to collect the data required to make those assessments and thereby provide the knowledge needed to make 

informed and sound policy.

Acknowledgements

We thank D.L. Mosier, R.A. Koski, Peter Stauffer, and 

H. Gibbons of the USGS for helpful comments on this manuscript. Many websites were consulted for historical and geographic background information, including those of the U.S. 

Office of Insular Affairs, the U.S. Department of State, government and cultural agencies of Federated States of Micronesia, Republic of the Marshall Islands, and Republic of Belau, 

and others.

Appendix 1. Metric System Conversion 

Factors

To change Multiply by

Kilometers to miles (statute) 0.62

Kilometers to miles (nautical) 0.54

Square kilometers to square 

 miles (statute) 0.39

Square kilometers to square 

 miles (nautical) 0.29

Miles (nautical) to kilometers 1.85

Square miles (nautical) to 

 square kilometers 3.43

Millimeters to inches 0.039

Centimeters to inches 0.39

Meters to feet 3.28

Appendix 2. Definitions and 

Explanations

Carbonate ooze. A sediment composed of greater than 

70 percent biogenic calcium carbonate (CaCO3) mud and silt. 

The biogenic carbonate consists mostly of plankton, predominantly foraminifera and nannoplankton tests.

Cobalt-rich iron-manganese crust. Iron-hydroxide and 

manganese-oxide (ferromanganese) deposits formed from 

direct precipitation of minerals from sea water onto hard-rock 

substrates, thereby forming crusts and pavements. Crusts contain minor but potentially economically important concentrations of cobalt, titanium, cerium, zirconium, nickel, platinum, 

and other metal and rare-earth elements. Minimum conditions 

considered for mining fall within the following ranges as determined by different workers: minimum cobalt content of 0.6 to 

0.8 percent; minimum crust thickness of 25 to 40 millimeters; 

minimum tonnage of 20 kilograms of crust per square meter.

Epithermal deposit. A mineral deposit formed by hydrothermal processes within about 1 kilometer of the Earth’s surface at temperatures of about 50 to 200°C.

Exclusive Economic Zone (EEZ). A zone 200 nautical miles (370 kilometers) wide that surrounds each island 

or island nation. EEZ boundaries shown in this circular are 

unofficial and were constructed by drawing arcs with a radius 

of 200 nautical miles from emergent parts of islands and lines 

equidistant between islands of different nations within 200 

nautical miles of one another.

GLORIA. A digital side-scan sonar system that images 

a wide swath of sea floor using reflected sound waves. Thus, 

large areas of the sea floor can be quickly mapped. It is an 

acronym for Geological LOng-Range Inclined Asdic. Detailed 

information can be found on the USGS Web site: U.S. exclusive economic zone (EEZ) GLORIA mapping program, http://

coastalmap.marine.usgs.gov/gloria (accessed September 2005).
Midway Island

Hawaii

Johnston Island

Palmyra AtollKingman Reef

Jarvis Island

American Samoa

Howland andBaker Islands

WakeIsland

Commonwealth of

Northern Mariana

Islands

Guam

Palau

Marshall Islands

Former Trust Territories

Federated States of

Micronesia

ALASKA

U.S.A.

Midway Atoll

Hawai'i

Johnston Atoll

Kingman ReefPalmyra Atoll

Jarvis Atoll

American Samoa

Howland andBaker Islands

WakeAtoll

Northern Mariana

Islands

Guam

Belau

Marshall Islands

Nations with Free Association with U.S.

Micronesia

10OS

0O

10O.

20O.

30O.40O.

50O.

100 150 OW 50O. 60O. 120O% 150O% 180O OW

40O.

30O.20O.

10O.

0O

10OS

120 120O% 150O% 180O 150OW OW

0 2,000km

IroncobrarezircIronnicHydgollea

L

No

Figure 21. Main potential deep-water mineral deposit type and contained metals for each Pacific EEZ of U.S. affiliation.
62 Marine Mineral Resources of Pacific Islands–A Review of the Exclusive Economic Zones

Hydrothermal deposits. A mineral deposit formed by 

precipitation from an aqueous fluid that is hotter than the 

ambient environment. These hydrothermal fluids are produced 

and circulate within the ocean crust by the heat of magmatic 

and volcanic processes. The fluid is usually seawater chemically altered by interaction with rocks that make up the ocean 

crust. Temperatures range from a few degrees above bottomwater temperatures to about 650°C. 

Iron-manganese nodules. Nodular deposits of iron 

hydroxide and manganese oxide (ferromanganese) that form 

on or near the sediment surface from direct precipitation of 

minerals from seawater and sediment pore waters. The nodular 

form reflects accretion of layers about a nucleus composed of 

a rock fragment or other material and episodic turning of the 

nodule on the sea floor throughout its growth history. Nodules are typically 1 to 6 centimeters in diameter. A general 

consensus is that a first-generation mine site requires an average abundance of nodules of 10 (minimum 5) kilograms per 

square meter, and the nodules should have an average nickelplus-copper content of 2.27 percent (minimum 1.18 percent).

Phosphorite. Sedimentary deposit of calcium phosphate 

that formed by precipitation from sediment and rock-pore fluids 

and by replacement of carbonate (limestone) rock and sediment. 

Phosphorite commonly contains chlorine, fluorine, and carbonate. Phosphorite forms on the flanks of seamounts, on the tops 

of submarine banks, and within reef islands and atoll lagoons. 

Phosphorite can also form from bird droppings (guano). Phosphorite is used mainly in agriculture as a fertilizer and in the 

food and beverage industry as a source of phosphoric acid.

Polymetallic sulfides/sulfates. Hydrothermally formed 

deposits of sulfide and sulfate minerals that contain concentrations of metals, including copper, lead, zinc, gold, and silver. 

Parts of the EEZs of Papua New Guinea, New Zealand, and 

Fiji have been, or are in the process of being, leased for exploration for polymetallic sulfides.

Pozzolan. Siliceous volcanic tuff (ash) that can be finely 

ground and combined in cement.

Pumice. Highly vesicular, glassy volcanic rock that is 

commonly buoyant enough to float. It is used as an abrasive 

and in lightweight cement.

Precious coral. The finest quality of coral, judged on 

the basis of beauty, color, hardness, and rarity. Precious corals 

include red and pink varieties (genus Corrallium), which can 

be found in water as deep as 1,500 meters. Black corals (Antipathes) occur in water depths from near the surface to about 

5,000 meters, but mostly between 10 and 100 meters. Gold 

corals (Gerardia and Primnoa) occur in deep water (mostly 

300 to 450 meters), as do bamboo corals (Acanella and Lepidisis). All these corals thrive in areas with hard substrates, little 

sediment input, and near-vertical faces with strong currents. 

The collection is prohibited for several species of corals in 

these genera, which are listed by the Convention on International Trade in Endangered Species (CITES).

Resource potential. We define “near-term” (also called 

“short-term”), “intermediate-term,” and “long-term” potential 

resource to mean, respectively, within the next 25 years, 25 

to 50 years, and more than 50 years. Even though a particular 

commodity may be given the same ranking for several EEZs, 

the global market and other factors may not support mining 

from more than one or two of the EEZs for that commodity 

Competing mining operations, technology innovations, environmental concerns, and changing economic, political, security, 

and land-use issues could significantly modify the resource 

potential estimates for the commodities considered here.

Seamount. A submarine volcano that may be active or 

may have been extinct for tens of millions of years. Seamounts 

do not extend above the ocean surface as islands, although 

they may have done so at one time. Flat-topped seamounts are 

called guyots and were at one time islands. Their tops were 

eroded flat by waves and the edifices sank following cessation 

of volcanic construction. Conical seamounts were likely never 

islands.

Siliceous ooze. A sediment composed of greater than 

70 percent biogenic silica mud and silt. The biogenic silica 

(SiO2

•nH2O) consists mostly of plankton, predominantly 

diatom frustules and radiolarian tests.

Skarn. A rock formed by chemical and physical alteration of a carbonate rock (limestone or dolomite) as the result 

of fluids and heat from of an igneous intrusion (contact metamorphism and metasomatism). Garnet-rich carbonate rocks 

and associated ore deposits may result from this transformation.

Appendix 3. Acronyms and Abbreviations

CNMI. Commonwealth of the Northern 

 Mariana Islands

DOS. U.S. Department of State

EEZ. Exclusive Economic Zone

FSM. Federated States of Micronesia

ISA. International Seabed Authority

MMS. U.S. Minerals Management Service

NOAA. U.S. National Oceanic and 

 Atmospheric Administration

OIA. U.S. Office of Insular Affairs

RMI. Republic of the Marshall Islands

SOPAC. South Pacific Applied Geoscience 

 Commission

U.N. United Nations

USGS. United States Geological Survey