Rocks and Minerals 

Make up Your World
 
 

Rock and Mineral
 

10-Specimen Kit
 

Companion Book
 

Presented in Partnership by
 

This mineral kit was also made possible through the generosity of the mining companies who 

supplied the minerals. If you have any questions or comments about this kit please contact the 

SME Pittsburgh Section Chair at www.smepittsburgh.org. 

For more information about mining, visit the following web sites: 

www.smepittsburgh.org or www.cdc.gov/niosh/mining 

Updated August 2011 
CONTENTS
 

Click on any section name to jump directly to that section. If you want to come back to 

the contents page, you can click the page number at the bottom of any page. 

INTRODUCTION 3
 

MINERAL IDENTIFICATION 5
 

PHYSICAL PROPERTIES 6
 

FUELS 10
 

BITUMINOUS COAL 12
 

ANTHRACITE COAL 13
 

BASE METAL ORES 14
 

IRON ORE 15
 

COPPER ORE 16
 

PRECIOUS METAL ORE 17
 

GOLD ORE 18
 

ROCKS AND INDUSTRIAL MINERALS 19
 

GYPSUM 21
 

LIMESTONE 22
 

MARBLE 23
 

SALT 24
 

ZEOLITE 25
 
INTRODUCTION 

The effect rocks and minerals have on our daily lives is not always obvious, but this 

book will help explain how essential they really are. If you don’t think you come in 

contact with minerals every day, think about these facts below and see if you change 

your mind. 

•	 Every American (including you!) uses an average of 43,000 pounds of newly 

mined materials each year. 

•	 Coal produces over half of U.S. electricity, and every year you use 3.7 tons of 

coal. 

•	 When you talk on a land-line telephone you’re holding as many as 42 different 

minerals, including aluminum, beryllium, coal, copper, gold, iron, limestone, 

silica, silver, talc, and wollastonite. 

•	 When you reach for a cell phone to send a text, know that you have at least nine 

different minerals in your hand, including copper, silver, gold, palladium, and 

platinum. 

•	 The digital alarm clock you rely to wake you up every morning relies on boron, 

copper, gold, and quartz to work. 

•	 Computers are made from more than 30 different minerals, including silver, gold, 

aluminum, and copper in the monitors; quartz in the glass; and calcite and 

gypsum in the keyboards. 

•	 Next time you get a in car, think of the many, many different minerals it took to 

make it, including iron, aluminum, carbon, copper, silicon, lead, zinc, manganese, 

chromium, nickel, magnesium, sulfur, platinum, gold, silver, and tin. 

•	 When you look out a window, appreciate the view, along with the silica and trona 

that make up the glass. 

•	 Make a mistake on your homework? Be thankful for the graphite, kaolin, and 

pumice that make the erasers that help you fix it. 

•	 Do you brush your teeth twice a day? Did you know that your toothpaste is made 

of calcium carbonate, zeolites, trona, clays, and silica? 

There are hundreds of minerals used regularly in the United States for defense, 

industrial, agricultural, residential, medical , and cosmetic purposes. The minerals 

provided in this kit are a small sample of the minerals that Americans likely encounter 

but take for granted each day. 

3
 
It is convenient when we discuss minerals to place them in different categories . The 

mineral information in this book has been grouped in the following four categories : 

• Fuels 

• Base Metals 

• Precious Metals 

• Industrial Rocks and Minerals 

There is a section in the kit for each of these categories. Within each category, you will 

find information on the specific minerals in your kit. Maps are included to show where 

these minerals are found in the U.S. 

Please Note: 

This companion book is designed to be a com plement to the 10 rock and mineral 

samples found in your kit . However, some kits could be different if a particular rock or 

mineral sample was not available. 

4
 
MINERAL IDENTIFICATION 

First, let’s go over the difference between a rock and a mineral . Rocks are essential 

building materials that make up the earth, while minerals are individual substances that 

make up rocks . Therefore, most rocks are aggregates, meaning they are made up of 

two or more minerals . Ore, for example, is an aggregate containing precious or useful 

metal along with other minerals that must be separated out before the metal can be 

used. Three of the samples in your kit are ore samples : iron, copper, and gold. 

There are three main types of rock found on earth: igneous, sedimentary, and 

metamorphic. 

Igneous—These rocks are made when magma (melted rock below the earth’s 

surface) or lava (the m elted rock that flows from volcanoes above the surface) 

cools and hardens. Most of the earth’s crust is made of igneou s rock. Granite is 

one example of igneous rock. 

Sedimentary—These rocks are made up of tiny pieces of rocks and minerals that 

have been worn away from larger rocks by wind and water. The small pieces 

settle somewhere and start piling up, layer after laye r, and eventually the lower 

layers turn into rock. Sandstone is one example of sedimentary rock. 

Metamorphic—These rocks are form ed when the heat and pressure found deep 

under the earth’s crust cause existing rocks —igneous, sedimentary, or 

metamorphic—to change into a different rock. Marble is one example of 

metamorphic rock. 

More than 3,500 minerals have been identified in the earth’s crust . Each mineral can be 

identified by its distinctive physical and chemical properties . 

Physical Properties: 

Luster 

Hardness 

Color 

Streak 

Cleavage (the way is splits) 

Fracture (the way it breaks) 

Specific gravity 

Other mineral properties 

Chemical Properties: 

Atomic structure 

Chemical composition 

5
 
PHYSICAL PROPERTIES 

Most minerals can be identified by examining the physical properties described below. 

Luster 

Luster is determined by the way light is reflected from a rock or mineral. Luster 

describes how glossy, or shiny, the surface is. The general appearance of the surface, 

how it reflects light, the scattering of light by tiny, microscopic flaws (called inclusions), 

and how much light passes through the mineral —these and m any other features are 

responsible for luster. Here are a few examples of luster: 

Metallic—The surface is opaque, meaning light does not pass through. It reflects 

light and looks like a typical metal, such as gold, silver, lead, copper, or 

aluminum. 

Vitreous—The surface reflects light like glass does; vitreous rocks and minerals, 

like the anthracite coal in your kit, are often called glassy. 

Greasy—The surface looks as if it has been coated in grease , like the salt in your 

kit. 

Other terms used to describe luster include silky, pearly, waxy, and dull. 

Hardness 

Hardness is one of the most useful properties for identifying a m ineral. Hardness can be 

defined as a measure of the mineral’s resistance to a force . There are several ways to 

apply force (scratching, indentation, and grinding), but t esting resistance to scratching is 

a popular way of determining hardness because it requires no special equipment. 

Hardness based on scratch testing was given a precise definition in 1822 by the 

Austrian mineralogist Friedrich Mohs, who proposed the following scale : 

 Mohs Scale of Hardness 

1. Talc (Softest) 6. Orthoclase 

2. Gypsum 7. Quartz 

3. Calcite 8. Topaz 

4. Fluorite 9. Corundum 

5. Apatite 10. Diamond (hardest) 

Each of these minerals will scratch those minerals lower in the scale, and will in turn, be 

scratched by those higher in the scale. So, gypsum can scratch talc (or any mineral 

lower than a 2) and it will be scratched by calcite (or any mineral higher than a 2). To 

give a real-world example, minerals softer than 2 1⁄2 will leave a mark when scratched 

across paper; here are some more hardness values for familiar objects: 

2 1⁄2 = Fingernail 

3 = Copper coin 

5 1⁄2 = Knife blade, Window glass 

Given those values, we can see that minerals under a hardness of 2 1⁄2 can be 

scratched by your fingernail. Minerals under a hardness of 5 1⁄2 can be scratched by a 

6
 
knife or piece of window glass . Minerals over a hardness of 5 1⁄2 will scratch a knife or 

piece of glass. 

Keep in mind that the minerals on the scale are just examples; they are not the only 

minerals with those hardness levels. Also, as you can see, some minerals fall between 

numbers on the scale and have hardness levels such as 3 1⁄2 or 5 3⁄4. 

Color 

The same mineral can come in a variety of colors, so we don’t usually rely on color to 

recognize them. Some minerals are almost always found in the same color, such as 

sulfur (yellow), gold, and silver , but many minerals have minor impurities , or flaws, that 

can cause color change. For example, quartz occurs in almost every color imaginable. 

When determining color, it should always be observed on a freshly broken piece of the 

mineral, because an older surface may be stained or worn down . 

Streak 

Streak is an important, simple test that can be used to identify some minerals . The color 

of a powdered mineral is called its streak, and it is usually obtained by rubbing the 

mineral against a piece of unglazed porcelain called a streak plate . Keep in mind that 

the color of a mineral’s streak may be different than the mineral itself . For example, 

hematite is black, but its streak is Indian red , earning it the nickname “bloodstone.” 

Cleavage 

Minerals that form in crystals are said to cleave or have cleavage when they break in a 

defined direction along a smooth surface . This property is the result of a precise pattern 

of atoms in regular layers that have weak connections in certain directions. Minerals 

may have cleavage in more than one direction if the atoms have a weak connection in 

multiple directions. For example, mica will flake into thin sheets because in has 

cleavage in a single direction . However, diamonds have cleavage in eight directions , 

allowing them to naturally form into the tradition al diamond shape; this property is used 

by diamond cutters to shape the diamond and remove flaws or impurities. 

Fracture 

Minerals that break in irregular directions are said to fracture . Fracture is described 

based on a freshly broken pattern . For example, fracturing quartz has a series of arcs, 

similar to patterns seen in sea shells, called “conchoidal” fracture s. This same pattern is 

found on chipped glass. Metals, however, have a “hackly” fracture, which results in a 

jagged surface that is uncomfortable to the touch . Common words used to describe 

mineral fractures include uneven, splintery, and blocky. 

Specific gravity 

Specific gravity is the relative weight of a mineral compared to the weight of an equal 

amount of water. Water is given a specific gravity of 1 and the specific gravity of a 

mineral is compared to it. So, if you have exactly one cup of water and one cup of a 

mineral, and the mineral weighs more, it has a higher specific gravity than water. 

Minerals vary in specific gravity . Some minerals are heavy for their size while others are 

light for their size. For example, lead (galena) and granite are very heavy for their sizes , 

7
 
while salt and talc are light for their sizes . Experience and judgment on handling 

minerals can help you make a good guess at the specific gravity for a mineral. 

Other mineral properties 

Some minerals have unusual physical properties that can be useful for recognizing 

minerals. 

Fizz—Some minerals fizz, or react, when they come in contact wi th an acid or 

household vinegar. The fizz is carbon dioxide gas escaping from the mineral . 

Calcite is an example of a mineral that fizzes. 

Striated—Some minerals, such as pyrite, have parallel, straight lines called 

striations on their smooth surfaces. 

Flexible—Some minerals, such as chlorite, can be bent and remain bent. 

Elastic—Some minerals will snap back to their original position if they are 

stretched (not broken) . Mica has elastic properties. 

Malleable—Malleable means the mineral can be hammered flat without falling to 

powder. Most metal minerals hav e malleable properties . 

Magnetic—Some minerals, such as magnetite and pyrrhotite, are attracted by a 

magnet. 

Fluorescent—Some minerals, such as fluorite, glow in the dark when they are 

exposed to ultraviole t light. The term fluorescent actually comes from the name 

for the mineral fluorite, but fluorite is not the only fluorescent mineral; m any 

diamonds are also fluorescent . This property is similar to phosphorescence, 

which also involves a mineral glowing in the dark. Phosphorescent minerals 

release light slower and for longer periods of time than florescent ones. 

Phosphorescence is similar to the glow -in-the-dark effect found in toys and other 

objects. 

Radioactive—A mineral is radioactive when the mineral’s atoms give off energy 

as they break down. Pitchblende (uraninite) and carnotite are t wo of the more 

common types of radioactive minerals. 

8
 
 

 

 

 

 

Table 1 provides a quick summary of the physical properties of the minerals in this kit, 

but each mineral is also explained in detail on the following pages. 

Hardness, streak, cleavage, and specific gravity are properties that typically belong to 

minerals, so four rocks in your kit—the two coals, limestone, and marble— don’t have 

information in some of those areas of the table. Your kit also contains three more rocks: 

iron ore, copper ore, and gold ore, but on this table the pure metals are described so 

you can learn their physical propert ies. 

Table 1. Summary of the Physical Properties of the Rocks and Minerals in Your Kit 

Rock or 

Mineral Luster Hardness Color Streak Cleavage Fracture Specific Gravity Other 

Bituminous 

Coal 

Dull 

to Greasy Varies Black Varies Varies Cleats Varies Rock 

Anthracite 

Coal Vitreous Varies Jet Black Varies Varies Conchoidal Varies Rock 

Iron Metallic 4.0–5.0 Gray Black Gray None Hackly 7.3–7.8 Magnetic 

Copper Metallic 2.5–3.0 Reddish 

Orange 

Reddish 

Orange None Hackly 8.95 

Ductile & 

Malleable 

Gold Metallic 2.5–3.0 Gold 

Yellow Yellow None Hackly 19.3 

Very 

ductile & 

malleable 

Gypsum Vitreous 2.0 Colorless White Perfect None 2.3 Soluble 

Limestone 

Dull 

to Pearly 

(polished) 

3.0 Varies Varies Varies Irregular to 

Subconchoidal 1.8–2.7 Rock 

Marble Dull 

to Pearly 3.0–4.0 Varies Varies Varies Irregular 1.8–2.9 Rock 

Salt Greasy 2.5 Colorless White Good None 2.1 Taste 

Zeolite Vitreous 4.0–5.0 Colorless White Perfect None 2.2 Light & 

Fragile 

9
 
FUELS

The fuel-type minerals included in your kit are bituminous and anthracite coal. Coal is a 

fossil fuel composed mostly of carbon, with traces of hydrogen, nitrogen, sulfur, and

other elements. Coal is far more plentiful than U.S. oil or natural gas, and it is removed 

from the earth by a process called mining. Mining occurs in both surface and 

underground operations. In 2007, there were 2,030 coal mines operating in the United

States. Approximately 93,000 coal miners produce over 1 billion tons of coal per year 

and create jobs in transportation, management, manufacturing and support industries. 

The map below shows where the mines are located. 

Figure 1. Location of coal mines (includes surface and underground mines).

Coal is a sedimentary rock deposited in layers, or beds, with other sedimentary rock. 

The oldest coal-forming period, the Carboniferous Period (also called Mississippi & 

Pennsylvania periods), occurred 300 to 360 million years ago and produced some of the 

world’s major coal deposits. Three thousand different species of plant life were alive 

during at that time; some ferns were the size of today’s trees, and some bushes were 

nearly 90 feet tall. 

All coal once existed as growing plants. When the plants died they started to break 

down, but being buried by other plants kept them from decaying entirely. The dead 

plants were then transformed into coal by a process called “coalification.” During 

coalification, the decaying plants are exposed to pressure and heat from being deeply 

buried. The pressure and heat bring on chemical changes in the plants: they first 

change into peat; then as more pressure and heat is applied, moisture and gases are 

10
forced out, and the remaining buried material consists mostly of carbon, the main 

element in coal. 

There are five stages of coalification, and each stage results in different physical and 

chemical properties. 

1.	 Peat—Partly-decomposed plants; about 50% carbon. 

2.	 Lignite—Light-brown, soft coal; about 70% carbon. 

3. Sub-bituminous—Low-luster, soft coal; about 80% carbon. 

4.	 Bituminous—Brittle, well-jointed, and blocky black coal; about 88% carbon. 

5.	 Anthracite—Hard, high-luster, jet-black coal exhibiting conchoidal fractures; about 

92% carbon. 

Coal is classified into different ranks by its behavior during heating; anthracite is the 

highest-ranked coal, and lignite is the lowest . This classification relies on measurements 

of moisture, volatile matter (parts of the coal given off during heating), and fixed carbon 

(the amount of carbon left after the volatile material is burned off) . Coal with lower fixed 

carbon content and a higher volatile matter and moisture content is a low rank coal . 

Coal with higher fixed carbon content and lower volatile matter and moisture content is 

a high rank coal . High rank coals provide more heat when they are burned . Coal is used 

for different purposes based on its ranking and on the mineral impurities it contains that 

could pollute the environment. 

In the U.S., coal provides over half of the electricity nationwide, meaning that it provides 

almost as much energy as gas, oil, hydroelectric, and nuclear power provide combined . 

It is relatively cheap to use coal to produce electricity, s o it helps keep costs down as 

we power the air conditioners, televisions, computers, and so many other things we 

need electricity to use. 

11
 
Bituminous Coal
 

GENERAL
 

Bituminous coal is an intermediate ranking coal , meaning it contains more carbon and 

gives off more heat than sub-bituminous and lignite coal, but it does not contain as 

much carbon or give off as much heat as anthracite coal. Most of the coal mined in the 

U.S. is bituminous. 

PHYSICAL PROPERTIES* 

[* Physical properties presented above are based on averages and/or purer minerals than in your kit.] 

Bituminous coal is a rock that is usually identified by how much carbon it contains rather 

than its physical properties , but knowing the physical properties can still be helpful . 

 

Color—Black
 

Luster—Dull to greasy
 

Fracture—It breaks easily into irregular blocks; vertical fractures (called cleats) 

down two sides of the blocks. 
 

Other—It is usually stratified, or banded, with thin, alternating shiny and dull 
 

layers.
 

Origin 

Eastern U.S. coal formed from the remains of plant life that existed about 300 million 

years ago. The ideal environment for coal formation is a swamp . As the plants die and 

fall into the swamp environment, they become waterlogged and sink . Bacteria decay the 

dead plant material , and it turns into peat. Through time, oxygen supplies in the water 

are used up, and eventually the bacteria can no longer continue to decay the plant 

matter, but the pressure and heat from being buried under layers of plants and dirt 

continue the coal-making process . Valuable coal deposits only occur if the swamp basin 

slowly sinks and mud or similar material buries the dead plants . Bituminous coal is the 

fourth stage of the coal-forming process. 

USAGE 

• Fuel source to generate electricity 

• Fuel source for industries 

• Chemicals 

o perfume 

o billiard balls 

o saccharin (a sweetener that is much sweeter than sugar) 

12
 
Anthracite Coal
 

GENERAL 
 

Anthracite coal, or hard coal, is the highest ranking coal . It is an ideal fuel because its 

high carbon content allows it to burn s lowly and cleanly (smoke free and odorless), 

maximizing heat output . 

PHYSICAL PROPERTIES* 

Anthracite coal is a rock that is usually identified by how much carbon in contains rather 

than its physical properties , but knowing the physical properties can s till be helpful. 

Color—Jet black 

Luster—Vitreous (Glassy) 

Fracture—Curved or irregular conchoidal 

Other—It is very hard and does not break easily. It also does not have the 

stratified, or banded, look that bituminous coal has. 

ORIGIN 

Eastern U.S. coal formed from the remains of plant life that existed about 300 million 

years ago. The ideal environment for coal formation is a swamp . As the plants die and 

fall into the swamp environment, they become waterlogged and sink . Bacteria decay the 

dead plant material, and it turns into peat. Through time, oxygen supplies in the water 

are used up, and eventually the bacteria can no longer continue to decay the plant 

matter, but the pressure and heat from being buried under layers of plants and dirt 

continue the c oal-making process. Valuable coal deposits only occur if the swamp basin 

slowly sinks and mud or similar material buries the dead plants . Anthracite coal forms 

in the last stage of the coal-forming process . 

USAGE 

• Fuel source 

• Mixed with other coals 

• Purifier for water 

[* Physical properties presented above are based on averages and/or purer minerals than in your kit.] 

13
 
BASE METAL ORES

Metals are versatile, meaning they have many different uses, which makes them very 

valuable for use in technology. Metals are malleable, meaning they can be bent and 

shaped without cracking, and ductile, meaning they can be stretched out into a thin 

wire. They are very good at conducting heat and electricity. Metals directly impact radio 

and television communication, aeronautics, rocketry, nuclear power, and the distribution 

of electricity. 

All the metals included in your kit (except for iron) are scarce, which means they make 

up less than 0.1% of the earth’s crust. Many experts believe that these resources will be 

the first to develop shortages in the future, which will make developing new technology 

difficult. 

Iron, on the other hand, is the second most abundant metal on earth (aluminum is the 

first). Iron makes up approximately 5% of the earth’s crust, and it accounts for 

approximately 90% of all metal consumed. 

The map shows where base and precious metals deposits are mined in the U.S. 

14

Figure 2. U.S. Base and Precious Metal Producing areas. Includes gold (lode and placer), copper ore, 

iron ore, lead and/or zinc ore, uranium, silver ore, alumina (mill), aluminum ore, manganese, 

molybdenum, rare earths, titanium, nickel, uranium-vanadium ores, platinum group, zircon, tungsten, 

vanadium, beryl, and tin ore.
Iron Ore
 

GENERAL
 

Iron is mainly found in the ores magnetite, he matite, and taconite. In the U.S., taconite 

is the kind of iron ore m ost often mined. Remember that an ore is a rock containing 

valuable metal that must be separated out from the other minerals in the rock. 

Iron is one of three naturally magnetic minerals on earth, along with cobalt and nickel . 

Magnetite, one of the main types of iron ore, was named for its magnetic properties . 

Though iron is useful for magnet making, over 99% of all iron mined is used to make 

steel. Iron is relatively weak on its own, but combined with carbon and other elements to 

make steel, it can be used to make buildings, cars, railroad tracks, and more. 

PHYSICAL PROPERTIES* 

Taconite 

Luster—Metallic
 

Hardness—4.0–5.0
 

Color—Gray black
 

Streak—Gray
 

Cleavage—None
 

Fracture—Hackly
 

Specific Gravity—7.3–7.8
 

Other—Magnetic
 

Taconite deposits are generally distinguished into four types of deposits: 

•	 Cherty Taconite—It is grayish to brownish—sometimes reddish—with a granular 

texture. 

•	 Silicate Taconite—Silicate is like cherty taconite , but it is light grayish-green. 

•	 Slaty Taconite—It has a banded or layered look . The bands may be very thin or 

reach one-inch thickness . The bands may be yellow, red, purple, green, gray, or 

black. It has sparkling grains of magnetite or hematite. 

•	 Mottled Taconite—It has a spotted or mottled appearance . The spots are
 

generally light in color and surrounded by gray or brownish iron oxides. 
 

ORIGIN 

Most iron deposits are found in igneous and sedimentary formations . They are also 

commonly found in banded sedimentary deposit s. How they formed is not completely 

understood, but we do know that the banded sedimentary deposits came from iron 

settling on the bottom of shallow seas over one billion years ago. 

USAGE 

•	 Over 99% of iron ore makes iron and steel 

•	 Magnets 

•	 Vitamins 

[* Physical properties presented are based on averages and/or purer minerals than in your kit.] 

15
 
Copper Ore
 

GENERAL
 

Copper is man’s oldest metal; it has been used for over 10,000 years . It’s still widely 

used today, sometimes just as it was thousands of years ago. Copper plumbing, which 

is very popular in building today, was found in working condition in the 5,000- year-old 

Pyramid of Cheops in Egypt. From the beginning copp er has been used for high-tech 

survival tools, like the axes of 10,000 years ago (high -tech for the time!) , and today 

surgeons are using copper-coated scalpels to save lives . 

PHYSICAL PROPERTIES* 

Pure Copper 

Luster—Metallic 

Hardness—2.5–3.0 

Color—Reddish orange (If the air around the copper is often damp, it will change 

to a reddish brown color. Eventually, it will develop a green coating, called a 

patina, that stops any further corrosion.) 

Streak—Reddish orange 

Cleavage—None 

Fracture—Hackly 

Specific Gravity—8.95 

Other—Copper is malleable and ductile. Being ductile, combined with its 

excellent ability to conduct electricity, makes it a great material for making wire. 

(Silver is the only thing better at conducting e lectricity, but it’s too expensive to 

use for wires.) 

. 

ORIGIN 

Copper occurs as a native metal (not as an ore) in only a few places, and the most likely 

place to find it is in the Keweenaw Peninsula of Michigan . Large deposits of copper ore 

are located in the United States, Chile, Zambia, the Democratic Republic of the Congo , 

Peru, and Canada. Most of the world’s copper is mined from large copper sulfide 

deposits. After it is mined it’s purified to remove the other parts of the ore and forms 

99.999% pure copper. 

USAGE 

• Wire for electrical industry 

• Plumbing 

• Cookware 

• Jewelry 

• Coins (Though U.S. pennies are now only copper -covered zinc) 

• Pesticides 

[* Physical properties presented are based on averages and/or purer minerals than in your kit.] 

16
 
PRECIOUS METALS

Precious metals are most commonly used to make money and jewelry. However, they 

are being used more and more in other industries. Similar to the base metals, silver and 

gold are malleable, ductile, and good conductors of heat and electricity. 

Silver is in demand in photography as well as the electrical industry (mentioned in the 

section on copper). Silver crystals are a part of camera film and picture paper, and they 

allow clear, highly accurate pictures to develop. However, digital cameras have cut 

down on some of the silver use in photography. Gold is another useful metal because it 

is so resistant to corrosion that it is almost indestructible, but it is so scarce and 

expensive that it is not used in industry as much as silver. 

The map (the same one presented in the base metal section) shows where base and 

precious metals are mined in the U.S. 

17

Figure 2. U.S. Base and Precious Metal Producing areas. Includes gold (lode and placer), copper ore, 

iron ore, lead and/or zinc ore, uranium, silver ore, alumina (mill), aluminum ore, manganese, 

molybdenum, rare earths, titanium, nickel, uranium-vanadium ores, platinum group, zircon, tungsten, 

vanadium, beryl, and tin ore.
Gold Ore
 

GENERAL
 

Man’s quest for gold has been going on since ancient times . Gold has been prized as 

an ornament, a display of wealth, and as a bartering tool . The search for gold has also 

played a major role in exploration and discovery, because European explorers were 

often searching for gold when they first arrived in North and South America. Today gold 

is still very popular in jewelry-making. 

PHYSICAL PROPERTIES* 

The gold ore sample in your kit could be basalt, latite, shale/siltstone, or breccia. Basalt 

is a dark black rock with many small, light -colored crystals, which are made of the 

mineral feldspar, or green crystals, which are made of the mineral olivine. Latite is a 

light white rock with feldspar crystals surrounded by gray rock. Shale/siltstone is a gray 

rock with hematite (a black to brick red mineral) stains on the fractures. Breccia is a 

mixture of latite, shale, and sometimes sandstone. 

The physical properties of pure gold are 

Luster—Metallic 

Hardness—2.5–3.0 

Color—Gold Yellow 

Streak—Yellow 

Cleavage—None 

Fracture—Hackly 

Specific Gravity—19.3 

Other—Gold is very malleable and ductile. 

ORIGIN 

Gold reserves are found in rock veins and placer deposits . Rock veins are a sheet of a 

separate mineral within a rock. They form when water flows through cracks in the rock. 

In the case of gold, water carries small pieces of gold in the rock and leaves them there 

to build up. Placer deposits form when gold is separated from other minerals by 

weathering or erosion and it flows down streams or rivers. The small flecks of gold build 

up in river bends, under waterfalls, or in other natural collection places. 

USAGE 

• Mostly jewelry and money 

• Computers 

• Communication equipment 

• Spacecraft 

• Jet aircraft engines 

• Art 

[* Physical properties presented are based on averages and/or purer minerals than in your kit.] 

18
 
ROCKS AND INDUSTRIAL MINERALS

Your kit contains the following rocks and industrial minerals: gypsum, limestone, 

marble, salt, and zeolite.

These rocks and minerals are often used as building materials. Building materials are 

the largest crop that we reap from the earth; we extract about 3 billion tons per year. 

Furthermore, building materials are the second most valuable mineral commodity after 

fossil fuels. (Fossil fuels include coal, petroleum (oil), and natural gas.) 

Because most building materials are not scarce like metals, they have little value as 

they are found in the ground, but when they are removed and processed to a useful 

form, they increase in value enormously. 

When attractive building stone deposits are discovered, the main concern is how to get 

the rock without destroying it. Other types of mining use aggressive methods, like 

blasting, which usually shatters the mineral or rock. However, with building stones, it is 

better to remove the stone at places where it naturally cracks or joins with another 

stone. 

The maps below show where nonmetal mining operations are located in the U.S 

19

Figure 3. U.S. nonmetal mining operations (includes clay, gypsum, shale, pumice, talc, soapstone and 

pyrophylite, barite, phosphate, perlite, feldspar, salt, mica, trona, potash, boron materials, vermiculite, 

leonardite, kyanite, magnesite, gilsonite, fluorspar, asbestos, oil sand, aplite, borate minerals, and 

lithium).
Figure 4. U.S. stone mining operations (includes limestone, granite, traprock, sandstone, stone, 

dimension, lime, slate, and marble).

Figure 5. U.S. sand and gravel operations.

20
Gypsum
 

GENERAL
 

Gypsum is extensively mined in many parts of the world a nd consists of 79% calcium 

sulfate and 21% water . Gypsum is the raw material for making plaster of Paris, which, in 

the past, was often used to make the inside walls of houses. Plaster of Paris got its 

name from the gypsum deposit in the Paris Basin in Fra nce. Now a m aterial called 

drywall is typically used in building, but it is still made of gypsum. Plaster of Paris is still 

used today to make casts for broken bones , though fiberglass casts are also very 

common. 

PHYSICAL PROPERTIES* 

Luster—Vitreous (glassy), pearly, silky 

Hardness—2.0 

Color—Colorless to transparent, white, gray, yellowish , or brown 

Streak—White 

Cleavage—Perfect to very good 

Fracture—None 

Specific Gravity—2.3 

Other—Dissolves in hydrochloric acid and water . Can be fluorescent (meaning 

the sample glows in ultraviolet light). 

ORIGIN 

Gypsum is found in sedimentary rocks where seawater has evaporated. 

USAGE 

• Plaster, wall board 

• Some cements 

• Fertilizer 

• Paint filler 

• Ornamental stone 

• Brewing industry 

• Flux in pottery making 

[* Physical properties presented above are based on averages and/or purer minerals than in your kit.] 

21
 
Limestone
 

GENERAL
 

Limestone usage is so widespread that we use it every day and we may not even be 

aware of it . For example, most roads today have limestone beneath them as part of 

their beds. Also, limestone has made a major impact on almost everyone’s education: 

blackboard chalk is limestone. When that fine white power is viewed under a 

microscope you can see the remains of single-celled animals called foraminifera that 

helped form the limestone. 

PHYSICAL PROPERTIES* 

Luster—Dull to pearly (when polished) 

Hardness—3.0 

Color—Varies. Deposits in southwestern Pennsylvania are usually gray -white 

Fracture—Irregular to subconchoidal 

Specific Gravity—1.8–2.7 

Other—Fizzes under hydrochloric acid 

Limestone consists mainly or entirely of calcite and calcium carbonate , but calcite is 

about the only thing common to all limestone. Limestone differs widely in texture, color, 

content, structure, and origin . Most of their diversity is the result of the physical and 

chemical properties of calcite. 

ORIGIN 

Limestone is a sedimentary rock that forms under an ocean or sea . Sea water contains 

less acid than fresh water (lakes and rivers). Since acid can dissolve calcium, and 

calcium is necessary for limestone accumulation, fresh water is not a likely place for 

limestone development. 

A wide range of sea life—from one-cell plants such as algae to specialized animals, 

such as corals—can contribute to limestone formation . The plants and animals extract 

calcium carbonate from the sea water and use it to build skeletons and shells . When 

these plants and animals die, their shells and skeletons sink to the ocean floor and 

make a large contribution to limestone deposits . 

USAGE 

• Portland cement and aggregate (used to make concrete) 

• Crushed stone for roads 

• Soil stabilizer 

• Paper, glass, fiberglass, porcelain, petrochemicals, insecticides 

• Chewing gum, Toothpaste 

• Antacids (heartburn m edication) 

• Food products—cereals and bakery items 

• Source of calcium essential to healthy bone and muscle development. 

[* Physical properties presented above are based on averages and/or purer minerals than in your kit.] 

22
 
Marble
 

GENERAL 

Marble is well-known for its use in building and sculpture. Many dignified buildings, such 

as banks, use marble to create an impressive look of strength and wealth. Sculptors 

value marble as well because it is easy to carve and looks good when sculpted. Many of 

the Italian Renaissance sculptors, like Michelangelo, used marble fo r their statues. 

PHYSICAL PROPERTIES* 

Luster—Dull to pearly 

Hardness—3.0–4.0 

Color—Varies. 

Fracture—Irregular 

Specific Gravity—1.8–2.9 

Marble is known for its colorful swirls, but it can be solid white, as seen in sculptures. If 

there were impurities in the original rock or impurities were introduced while the rock 

was being changed into marble, they tend to group together in knots or spread into 

wavy streaks, giving the multicolored patterns for which marble is known. Also, the 

same process that changed the parent rock (limestone or dolomite) to marble causes 

the grains in the limestone and dolomite to grow , become visible crystals, and give the 

surface a liv ely sparkle. 

ORIGIN 

Marble is a metamorphic rock . It is formed as the result of deep buri al and an increase 

in temperature and pressure, possibly resulting from tectonic activity (mountain 

building), or hydrothermal activity (the movement of hot water) . Most marble deposits 

result when the rocks limestone or dolomite are subjected to increases in temperature 

and pressure. 

USAGE 

• Dignified buildings 

• Monuments (Tomb of the Unknown Soldier) 

• Decoration (Clocks, pen holders, etc.) 

[* Physical properties presented above are based on averages and/or purer minerals than in your kit.] 

23
 
Salt
 

GENERAL 

Salt has had a profound impact on the history of man . It has promoted exploration, 

warfare, conquest, and trade . Salt has been used as basis for gov ernment taxation and 

payment for services. Salt was also used to pay soldiers of the Roman Empire in a 

payment called “Salarium argemtum.” The English word “salary” is derived from this 

Latin term. 

In addition to its historical importance, s alt is an essential nutrient for the existence of 

life. Because you lose salt in sweat, tears, and other body functions , you need to eat 

salt to keep your hydration in check. In a year, you consume approximately 12 pounds 

of salt. 

PHYSICAL PROPERTIES* 

Luster—Greasy 

Hardness—2.5 

Color—Colorless, white to blue 

Streak—White 

Cleavage—Good cleavage 

Fracture—None 

Specific Gravity—2.1 

Other—Dissolves easily in water, and tastes salty 

ORIGIN 

Common salt is the mineral halite . Salt deposits are basically derived from evaporation 

of salt water, which is also called a brine solution. When the water evaporates , the salt 

separates and stays behind. The more common brine solutions include ocean water, 

salt lake water, and those found under the earth’s surface. The salt in your kit is called 

“extra coarse solar salt,” which means it was obtained by evaporation of a brine 

solution. 

Salt can also be obtained from solid deposits . The most common solid deposits are 

sedimentary beds, salt domes (a dome-shaped formation of salt within a rock) , or playa 

deposits (collections of salt that form where lakes have dried) . 

USAGE 

• Plastic products for building and construction 

• Soaps and detergents 

• Home furnishings 

• De-icing on highways 

• Canning 

• Water and sewage treatment 

• Table salt 

[* Physical properties presented above are based on averages and/or purer minerals than in your kit.] 

24
 
Zeolite
 

GENERAL 

The name zeolite comes from two Greek words meaning “to boil” and “stone.” It refers 

to the swelling-up and apparent boiling that occurs when this mineral is heated and 

water is driven off. Zeolites have the unique ability to not only lose water , but absorb 

water and other compounds, such as methane and carbon dioxide . Zeolites were first 

identified in 1756. They were considered geologic o ddities and were collectable items . 

Zeolite is actually referred to as a family of minerals that are aluminum silicates . Some 

of the more common zeolite minerals include: chabazite, clinoptilolite, erionite, and 

mordenice. The sample in your kit is one of these minerals. Zeolite deposits are 

abundant and can be mined at a low cost . 

PHYSICAL PROPERTIES* 

Luster—Vitreous to pearly 

Hardness—4.0–5.0 

Color—Colorless, white, sometimes red stains 

Streak—White 

Cleavage—Perfect 

Fracture—None 

Specific Gravity—2.2 

Other—It gives off water when heated and is very light and fragile. 

ORIGIN 

Zeolite deposits are formed from reactions between volcanic rock and water. For the 

most part, zeolites occur in the cavities and veins of igneous and sedimentary rock s. 

USAGE 

• Ionic exchanger in environmental cleanup and water purification. 

• Dimension stone 

• Insulation 

• Food supplement 

• Soil conditioner 

• Detergent 

• Medical 

• Filler in paper 

[* Physical properties presented are based on averages and/or purer minerals than in your kit.] 

25