Sand-Calcite Crystals from 

Garfield County, Utah 

By K. A. Sargent and H. D. Zeller 

New occurrence of 

sand-calcite crystals 

found in the 

Morrison formation of 

southern Utah 

U.S. GEOLOGICAl SURVEY BUllETIN 1606 
DEPARTMENT OF THE INTERIOR 

WilliAM P. ClARK, Secretary 

U.S. GEOlOGICAl SURVEY 

Dallas L. Peck, Director 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1984 

Library of Congress Cataloging in Publication Data 

Sargent, Kenneth A. 

Sand-calcite crystals from Garfield County, Utah. 

(Geological Survey Bulletin; 1606) 

Bibliography: 15 p. 

Supt. of Docs. No.: I 19.3:1606 

1. Calcite crystals. 2. Calcite-Utah-Garfield County. 

I. Zeller, H. D. (Howard Davis), 1922- .II. Title. III. Series. 

QE75.B9 no. 1606 557 .3s [549' .782] 

For sale by the Branch of Distribution 

U.S. Geological Survey 

604 South Pickett Street 

Alexandria, VA 22304 

83-600234 [QE39l.C2] 
CONTENTS 

Abstract 1 

Introduction 1 

Mineralogy 1 

Physical character of the crystals 1 

Petrography and crystallography 2 

Insoluble-residue and specific-gravity analyses 2 

Selected references 3 

FIGURES 

1. Index map of south-central Utah showing location of Escalante and area of 

figure 2 6 

2. Map showing Escalante and access to sand-calcite crystal locality 7 

3. Photograph of sandstone horizon in Morrison Formation containing sand-calcite 

crystals 8 

4. Stratigraphic section showing position of sand-calcite crystals in the Morrison 

Formation 8 

5-10. Photographs showing: 

5. Outcrop face with sand-calcite crystals weathering to ellipsoidal 

shapes 8 

6. Single sand-calcite crystals showing typical shapes 9 

7. Double sand-calcite crystals showing varieties of interpenetration or 

growth twins 10 

8. Sand-calcite crystals showing complex interpenetration or growth 

twins 11 

9. Sand-calcite growth twins showing relict bedding planes 11 

10. Broken complex sand-calcite crystal cluster with radiating pattern 12 

11. Photomicrograph of sand-calcite crystal showing rounded to subrounded detrital 

grains of quartz, feldspar, and chert in optically continuous matrix of 

calcite 13 

12. Photomicrograph of sand-calcite twin showing composition plane between 

penetration twins 13 

13. Line drawings of ditrigonal scalenohedrons 14 

14. Diagram of two sand-calcite crystals showing angles measured normal to 

C-axis 14 

15. Photograph of sand-calcite crystals showing corresponding top and side 

views 15 

TABLES 

1. Modal analyses of sand-calcite crystals from Garfield County, Utah 2 

2. List of locations of sand-calcite crystals giving percent calcite, and age and name 

of enclosing beds 3 

Contents Ill 

Sand-Calcite Crystals from Garfield County, Utah 

By K. A. Sargent and H. D. Zeller 

Abstract 

Sand-calcite crystals are found in the Morrison Formation of Jurassic age in south-central Garfield County, 

Utah. The outcrop area is less than 1 acre, yet the locality 

contains many fine specimens of single, double, and 

complex crystals in good hexagonal form. This is the first 

known occurrence of sand-calcite crystals in rocks of Jurassic age and is the first reported occurrence in Utah. 

INTRODUCTION 

Sand-calcite crystals are calcite crystals that include 

a large percentage of silt- to sand-size clastics. Many crystals, when removed from the enclosing matrix, exhibit 

well-developed scalenohedral forms. The locality reported 

here occurs on a ridge between two canyons that drain 

run-off from the Straight Cliffs in south-central Garfield 

County, Utah (fig. 1). The area of the deposit is somewhat 

less than 1 acre and is located in sec. 24, T. 36 S., R. 

3 E. (fig. 2). It can be reached by an improved dirt road 

going south about 16 km from the town of Escalante and 

then by hiking about 1.5 km southeast from the road. 

The crystals occur in a clean, white, poorly indurated sandstone of the Morrison Formation of Late Jurassic 

age (fig.3). The crystal-bearing zone is lens shaped. 

and attains a maximum thickness of about 4. 5 m. Crystal 

occurrence and quality vary both vertically and horizontally, and many crystals are concentrated along vertical 

zones. The abundance of crystals abruptly decreases both 

upward and downward from the lens-shaped zone. The 

base of the crystal zone is about 16 m above the base 

of the formation. The top of the formation is eroded at 

the crystal locality, but if the Morrison section were complete, the sand-calcite crystals would be about 36 m below 

the top of the formation (fig. 4). The crystals were probably formed by aqueous solutions charged with calcium 

carbonate that precipitated in the pore spaces around detrital sand grains. Crystal growth at nucleation centers of 

the calcium led to the formation of large calcite euhedra. 

Where several growth centers were close to each other, 

and where calcite euhedra grew simultaneously, the crystals formed penetration twins. It is not clear why this section of the Morrison Formation was the site for crystal 

growth, nor is it clear when the crystals formed. Sources 

of the calcium carbonate could be from some of the overlying calcareous beds in the Dakota Sandstone and Tropic 

Shale, both of Cretaceous age. 

The locality was discovered in October of 1968 by 

H. D. Zeller of the U.S. Geological Survey and F. J. 

Alvey of Esc:alante, Utah. Zeller (1973) has published on 

the geology of the area. 

This is the first known occurrence of sand-calcite 

crystals in Utah, and is the first reported occurrence in 

rocks of Jurassic age. Other reported localities are in rocks 

of Precambrian age (Weiblen, 1963), Triassic age 

(Fuhrman, 1968), and Late Permian age (Kadunas, 1967). 

The best known localities, which are famous for their 

beautifully formed crystals, are in beds of Tertiary age 

in South Dakota (Barbour, 1901) and in France (Lacroix, 

1901). 

Well-formed scalenohedron crystals such as are 

found here are rare in the United States, and it has been 

recommended to the Bureau of Land Management that 

the public land on which they occur be open to restricted 

collecting by permit only. 

The authors wish to thank Donald M. Cheney for 

determining percent of insoluble material and obtaining 

specific-gravity values on four sand-calcite crystals. Dawn 

Reed did the photographic work on whole crystals, and 

Louise Hedricks did the photography of thin sections. The 

authors also thank Eugene E. Foord and Allen V. Heyl 

for checking the crystal forms. 

MINERAL<>GY 

Physical Character of the Crystals 

The crystals weather out of the sandstone horizon 

in a variety of shapes and sizes. Many of those exposed 

to weathering are now ellipsoidal (fig. 5). Others still retain good hexagonal forms as single crystals (fig. 6), double interpenetration crystals or growth twins (fig. 7), and 

more complex compound crystals (fig. 8). Length ranges 

from about 2 em for single crystals to as much as 30 

em for crystal clusters. The average crystal is 5 to 10 

em in length. Some weathered crystals show the relict 

bedding plane of the sandstone formation (fig. 9). Some 

rare forms show radiating patterns (rosettes) on broken 

surfaces (fig. 10). 

Mineralogy t 
Table 1. Modal analyses of sand-calcite crystals from Garfield County, Utah 

[Values are in percent by volume] 

Sample Calcite Chert and Heavy 

Number matrix Quartz quartzite feldspar Siltstone Shale minerals Total 

K-79-1 40.79 52.95 3.67 1.06 1.06 0.77 0.19 99.99 1

K-79-2 35.98 57.22 3.78 .94 1.32 .76 .00 100.00 

K-79-3 36.27 57.16 4.45 1.26 .29 .48 .09 100.00 

K-79-4 37.83 54.90 4.73 1.75 .09 .70 .00 100.00 

1

Section cut normal to (0001). Other sections are without particular reference to crystallographic directions. 

Petrography and Crystallography 

Microscopic investigation showed the enclosed sand 

grains to be mostly quartz, chert, and quartzite with minor 

amounts of feldspar, siltstone, shale, and the heavy minerals-hornblende, pyroxene, biotite, zircon, magnetiteilmenite, hematite, and garnet-in an optically continuous 

calcite matrix (fig. 11). Results of modal analyses of four 

thin sections of sand-calcite crystals are shown in table 

1. 

The detrital grains range in diameter from 0.1 to 

0. 7 mm, most are from 0.1 to 0.3 mm. Quartz and feldspar grains are mostly rounded to subrounded, whereas 

shale and especially chert tend to be subangular and elongate. Quartz and all other detrital grains are in random 

orientation. Composition planes between interpenetration 

and growth crystals are generally irregular (fig. 12). 

The southern Utah sand-calcite crystals belong in 

the ditrigonal scalenohedral class of the hexagonal system 

(fig. 13). The forms appear nearly identical to, although 

slightly stubbier than, those described by Barbour (1901) 

from Devil Hill, S. Dak. As is true of all ditrigonal 

scalenohedrons, crystals rotated about the C-axis show 

similar scalene faces every 120°. For such crystals, careful 

. measurement between scalene faces on four crystals shows 

angles that are less than 120° alternating with those that 

are greater than 120° (fig. 14). The crystals are 

scalenohedrons but, because of the sand inclusions, many 

of their faces are poorly developed, and the zigzag pattern 

(fig. 13) that connects lateral edges is difficult, though 

not impossible, to discern. Moreover, the faces do not 

lie in flat planes, but are slightly bowed both vertically 

and laterally (fig. 15) as are those described by Barbour 

(1901, p. 171). This bowing imparts to the crystals a distorted look, as if they had been given a right-hand, or 

clockwise, twist from the top of the C-axis while the bottom was held in place. All the scalenohedrons have 

rounded terminations~ and probably are formed by the 

combination of one or more sets of rhombohedral planes 

(fig. 13B). No prismatic or pinacoidal faces are believed 

tQ exist on the Garfield County sand-calcite crystals. 

l Sand--Calcite Crystals from Garfield County, Utah 

Insoluble-Residue and 

Specific-Gravity Analyses 

Analyses of the percent of insoluble material of four 

crystals were performed by D. M. Cheney of the U.S. 

Geological Survey. 

Sample Original Crushed Residue Weight Percent Percent 

Number weight weight weight loss soluble insoluble 

grams material material 

1 38.57 38.54 26.54 12.00 31.1 68.9 

2 27.03 27.01 18.46 8.55 31.7 68.3 

3 31.00 30.95 20.98 9.98 32.2 67.8 

4 38.70 38.54 26.44 12.10 31.4 68.6 

Average------------------------------------------ 31.6 68.4 

Weights were taken on the intact samples as a reference, but measured losses and percent loss were determined from the weight obtained after crushing. Samples 

were treated with an excess of 6N HCI, then washed, 

filtered, and dried. 

Soluble calcite in the southern Utah crystals averages 31.6 percent by weight. This figure is lower than 

any other reported in the literature (table 2). The lower 

content of calcite in the Utah specimens may be due to 

the lower initial porosity of the fine to medium sand. 

Dry bulk -density determinations on four bulk samples gave results ranging from 2.56 to 2.67 g/cm3 . Because of the wide variation in these values for crystals 

that otherwise appeared to be mineralogically consistent, 

other methods were used to narrow the range in specificgravity determinations. Two samples were measured by 

the water displacement method, with results of 2.62 and 

2.67 g/cm3 • The outer surface of the crystals, however, 

is porous, and two other samples were checked for specific 

gravity after being coated with a thin layer of paraffin 

(p=0.89), with results of 2.57 and 2.60 g/cm3 . These 

last values are low probably because the paraffin did not 
Table 2. List of locations of sand-calcite crystals giving percent calcite, and age and name of enclosing beds 

Location 

Age and name of enclosing 

beds as reported 

Soluble matter 

(in percent) Source of data 

Cholame Hills, Early Miocene, Santa 35 (approx.) Rogers and Reed ( 1926). 

Monterey County, Calif. Margarita Formation. 

Devil Hill, S. Dale ............. Miocene, Arikaree Formation ....... 35.60 to 39.93 (36.19 ave) Barbour (1901). 

Rattlesnake Butte, S. Dak .... Early Miocene .......................... 36.95 to 37.00 Wanless (1922). 

Goshen Hole, Wyo ............. Miocene, Arikaree Formation ....... 36.37 (crystal) Barbour and Fisher (1902). 

Do............................. Do ...................................... 37.46 (concretion) Do. 

Bad Lands, Miocene, "White River 40 Penfield and Ford (1900) 

Washington County, S.Dak. sandstone." 

Fontainebleu, France ............ Oligocene marls ........................ 37 to 50 Nichols ( 1906). 

Mitchell region, Early Oligocene, 41.11 Barbour and Fisher (1901). 

Sioux County, Nebr. Chadron Formation. 

Stoneham, Colo .................. Oligocene ................................ 41.4 Campbell and Mitchell ( 1961). 

Salton, Calif ...................... Not reported, 70.83 (concretion) Nichols (1906). 

(probably Quaternary). 

saturate the sample all the way to the solid sand-calcite 

surface. Using modal values of 37.83 percent for calcite 

and 62.17 percent for silica sand, the calculated specific 

gravity of a sand-calcite crystal would be about 2.66 gl 

cm3 . By way of comparison, Nichols (1906) reported a 

range in specific gravity of sand-calcite crystals from 2.42 

g/cm3 (from Fontainebleau, France) to 2.69 g/cm3 (concretions from Salton, Calif.). Specimens from Saratoga 

Springs, N.Y., were reported at 2.62 g/cm3 , and those 

from Devil Hill, S. Dak. at 2.64 g/cm3 (Nichols, 1906). 

SELECTED REFERENCES 

Barbour, E. H., 1901, Sand crystals and their relation to certain 

concretionary forms: Geological Society of America Bulletin, v. 12, p. ll65-172. 

Barbour, E. H., and Fisher, C. A., 1902, A new form of calcitesand crystal: American Journal of Science, v. XIV, p. 

451-454. 

Campbell, F. H., HI, and Mitchell, R. S., 1961, Sand-calcite 

crystals from Stoneham, Colorado: Rocks and Minerals, 

v. 36, p. 18-21. 

Connolly, J. P., 1930, The sand-calcite crystals of Devils Hill: 

The Black Hills Engineer, v. 18, p. 264-273. 

Fuhrmann, Werner, 1968, "Sandkristalle" un Kugelsandsteine: 

lhre Rolle bei der Diagenese von Sanden, Aufshluss, v. 

19, no. 5, p. ll05-111. 

·. U.S. GOVERNMENT PRINTING OFFI{;E: 1984 0-46l-4H}l0100 

Kadunas, V. B., 1967, Ob izvestnyakovykh styazheniyakh v 

verkhnepermskikh otlozheniyakh severnoy chasti Pol'skoLitovskoy (Baltiyskoy) sineklizy, in Voprosy geologii 

srednego i verkhnego paleozoya Pribaltiki: Institute of 

Geology, Riga, p. 201-207.-[Calcareous concretions in 

upper Permian deposits of the northern part of the PolishLithuan:ian (Baltic) syncline.] 

Lacroix, A., 1901, Mineralogie de la France: Paris, France, v. 

3, p. 515-517. 

Nichols, H. W., 1906, Sand-calcite concretions from Salton, 

Califomia, in New forms of concretions: Field Columbian 

Museum, Geology Series, v. III. no. 3, p. 25-54. 

Penfield, S. L., and Ford, W. E., 1900, Siliceous calcites from 

the Bad Lands, Washington County, South Dakota: 

Americ:m Journal of Science, v. IX, p. 352-354. 

Rogers, A. F., and Reed, R. D., 1926, Sand-calcite crystals 

from Monterey County, California: American 

Mineralogist, v. 11, no. 2, p. 23-28. 

Wanless, H. R., 1922, Notes on sand calcite from South Dakota: 

American Mineralogist, v. 7, p. 83-86. 

Weiblen, Paul, 1963, Structure of concretions in the Thomson 

Formation, Carlton and Pine Counties, Minnesota, 

Abstract in Institute on Lake Superior Geology: 9th Annual Meeting, University of Minnesota, Department of 

Geology, Duluth, p. 16. 

Zeller, H. D., 1973, Geology map and coal resources of the 

Dave Canyon quadrangle, Garfield County, Utah: U. S. 

Geological Survey Coal Investigations Map C-59, scale 

1:24,000. 

Selected References 3 

FIGURES 1-15 
K A N E Areaaffj 

figure 1 

Figure 1. Index map of south-central Utah showing location of Escalante and area of figure 2. 

6 Sand-Calcite Crystals from Garfield County, Utah 
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KILOMETERS 

Figure 2. Location of Escalante and access to sand-calcite crystal locality (shaded area at end of 

arrow). Double dashes are improved dirt roads, solid lines are paved roads. Hachures are on 

cliff side of Kaiparowits Plateau and smaller mesas. 

Figures1-15 7 
Figure 3. Sandstone horizon (within dashed boundaries) 

in Morrison Formation containing sand-calcite crystals. 

Looking east, Henry Mountains in distance at far right. 

Photograph by H. D. Zeller, June 1981. 

DAKOTA SANDSTONE, LOWER(?) CRETACEOUS 

Grayish-orange sandstone interbedded with 

light-olive-gray shale in upper part; brownish-black carbonaceous mudstone and 

some beds of grayish-orange sandstone in 

lower part; locally includes conglomerate 

channel deposits at base 

r.-~-: .. ..:.. ...:.._-:-'-'-. .:....-:-.""'_~rL-------- UNCONFORMITY------

o ~ o I : •, o o.. • o 

.. ... . : . : · .. • f ••• 

. . - ...... ·.··:: ..... 

· .. -.· · . . :--:-_: ····~ · · ·· 7.6m 

. -·-.-· ~~~- · .. :. ·: ....... ·. 

MORRISON FORMATION, UPPER JURASSIC 

Gray sandstone and conglomerate. Pebbles of 

red chert, limestone, petrified wood, and 

quartzite in upper part. Light-gray massive 

fine-grained sandstone and interbedded 

greenish-gray and reddish-brown shale in 

lower part 

Grayish-olive siltstone and claystone 

White sandstone, poorly indurated; contains 

sand-calcite crystals in lower part 

Reddish-gray shale and siltstone 

Light-gray fine-grained sandstone; buff to 

yellowish ra on weatherin 

Reddish-gray shale and interbedded fine -

grained reddish-brown sandstone 

Red- and gray-mottled and yellowish-gray 

limestone, coarse! cr stalline 

Reddish-gray siltstone; forms slopes; some 

grayish-olive cia stone 

ENTRADA SANDSTONE, UPPER JURASSIC 

White to pale-orange, fine -grained sandstone; well-rounded and frosted grains; 

eolian crossbedding prominent 

Figure 4. Stratigraphic section showing position of sandcalcite crystals in the Morrison Formation. Dakota Sandstone and uppermost Morrison Formation are not present at sand-calcite crystal locality. 

8 Sand-Calcite Crystals from Garfield County, Utah 

Figure 5. Outcrop face with sand-calcite crystals weathering to ellipsoidal shapes. Rod is 2 m long. Photograph 

by H. D. Zeller, june 1981. 
Figure 6. Single sand-calcite crystals showing typical shapes. Some show small penetration twins. Photograph by 

Dawn Reed, 1980. 

Figures 1-15 9 
Figul'e 7. Double sand-calcite crystals showing varieties of interpenetration or growth twins. Photograph by 

Dawn Reed, 1980. 

10 Sand-Calcite Crystals from ·Garfield County, Utah 
Fi:gure 8. Sand-calcite crystals showing complex inter-

-penetration or growth twins. In the center is a complex 

double crystal. Photograph by Dawn Reed, 1980. 

Figure 9. Sand-calcite growth twins showing relict bedding planes. Photograph by Dawn Reed, 1980. 

Figures 1-15 11 
Figure 10. Broken complex sand-calcite crystal cluster (rosette) with radiating pattern. Photograph by Dawn Reed, 

1980. 

12 Sand-Calcite Crystals from Garfield County, Utah 
Figuue 11. Photomicrograph of sand-calcite crystal 

showing rounded to subrounded detrital grains of 

quartz, Q, feidspar, F, and chert, Ch, in optically continuous matrix of calcite, Ca. Calcite shows one dire~ction 

of cleavage. Crossed nkols, SOX magnification. Photograph by Louise Hedricks, 1980. 

Figure 12. Photomicrograph of sand-calcite twin showing composition plane (dashed line) between penetration 

twins. Plane has irregular trace. Crossed nico1s, 27X magnification. Photograph by Louise Hedrkks, 1980. 

figuRS 1-lS ll 
Figure 13. line drawings of ditrigonal 

scalenhdrons. A, Idealized crystal having 12 similar scalene faces; 8, Idealized crystal with rhombohedral terminations of scalene faces typical of 

sand-calcite crystals found in southern Utah. 

Note zigzag patterns at lateral edges (arrows) 

which are typical of this form. 

14 • Sand-Calcite Crystals from Garfield County, Utah 

Figure 14. Diagram of two sand-calcite 

scalenohedrons showing angles measured in plane normal to C-axis (measurements are shown on outside edge 

of diagrams). As for all such crystals, angles of . sca,lene faces greater than 120° 

(shaded) alternate with angles less than 

120°. Angles shown near center of crystals are supplementary. Error in reading 

angles is generally about 2°. Because 

surfaces are curved (shown as dotted 

line), measurements must be made 

tangentially. 
., 

ao· 

c 

~ ... 

.!.. 

loll 

... 

loll 

Figure 15. Sand-calcite crystals showing corresponding top and side views. Crystals show various degrees of curvature 

of scalene faces. Photograph by Dawn Reed, 1980.