For convenient reference, the Texas minerals described in this book are listed below, together with their chemical compositions, specific gravities, and hardness. You will be able to find similar information about additional minerals in mineralogy textbooks such as those noted on page 24.
| Mineral | Composition | Specific Gravity | Hardness |
| Albite | NaAlSi₃O₈ | 2.62 | 6 |
| Almandite | Fe₃Al₂ (SiO₄)₂ | 4.2 | 7 |
| Amphibole asbestos | Ca₂Mg₅Si₈O₂₂(OH)₂ | 3.0-3.3 | 1-2½ |
| Anhydrite | CaSO₄ | 2.9 | 3-3½ |
| Argentite | Ag₂S | 7.3 | 2-2½ |
| Azurite | Cu₃(CO₃)₂(OH)₂ | 3.77 | 3½-4 |
| Barite | BaSO₄ | 4.5 | 3-3½ |
| Biotite | K(Mg, Fe)₃AlSi₃O₁₀(OH)₂ | 2.8-3.2 | 2½-3 |
| Braunite | 3MnMnO₃MnSiO₃ | 4.75-4.82 | 6-6½ |
| Calcite | CaCO₃ | 2.72 | 3 |
| Carnotite | K₂O·2UO₃·V₂O₅·nH₂O | 5.03 | 2 |
| Cassiterite | SnO₂ | 6.8-7.1 | 6-7 |
| Celestite | SrSO₄ | 3.95-3.97 | 3-3½ |
| Cerargyrite | AgCl | 5.5 | 1-1½ |
| Chalcocite | Cu₂S | 5.5-5.8 | 2½-3 |
| Chalcopyrite | CuFeS₂ | 4.1-4.3 | 3½-4 |
| Cinnabar | HgS | 8.10 | 2½ |
| Dolomite | CaMg(CO₃)₂ | 2.85 | 3½-4 |
| Feldspar (see Albite, Microcline, Orthoclase) | |||
| Fluorite | CaF₂ | 3.18 | 4 |
| Galena | PbS | 7.4-7.6 | 2½ |
| Garnet (see Almandite, Grossularite) | |||
| Gold | Au | 15.0-19.3 | 2½-3 |
| Graphite | C | 2.2 | 1-2 |
| Grossularite | Ca₃Al₂(SiO₄)₃ | 3.53 | 6½ |
| Gypsum | CaSO₄·2H₂O | 2.32 | 2 |
| Halite | NaCl | 2.16 | 2½ |
| Hematite | Fe₂O₃ | 5.26 | 1-6½ |
| Hollandite | MnBaMn₁₆O₁₄ | 4.7-5 | 4-6 |
| Limonite | FeO(OH)·nH₂O | 3.6-4.0 | 1-5½ |
| Magnetite | Fe₃O₄ | 5.18 | 6 |
| Malachite | Cu₂CO₃(OH)₂ | 3.9-4.03 | 3½-4 |
| Mica (see Muscovite, Biotite) | |||
| Microcline | KAlSi₃O₈ | 2.54-2.57 | 6 |
| Muscovite | KAl₃Si₃O₁₀(OH)₂ | 2.76-3.1 | 2-2½ |
| Opal | SiO₂·nH₂O | 1.9-2.2 | 5-6 |
| Orthoclase | KAlSi₃O₈ | 2.57 | 6 |
| Pitchblende | UO₂ | 6.5-8.5 | 5½ |
| Pyrite | FeS₂ | 5.02 | 6-6½ |
| Pyrolusite | MnO₂ | 4.75 | 1-2 |
| Quartz | SiO₂ | 2.65 | 7 |
| Serpentine | Mg₃Si₂O₅(OH)₄ | 2.48 | 3-4 |
| Silver | Ag | 10.5 | 2½-3 |
| Sulfur | S | 2.05-2.09 | 1½-2½ |
| Talc | Mg₃Si₄O₁₀(OH)₂ | 2.7-2.8 | 1 |
| Topaz | Al₂SiO₄(F,OH)₂ | 3.4-3.6 | 8 |
| Tourmaline | Complex silicate of boron and aluminum | 3.0-3.25 | 7-7½ |
| Uranophane | CaO·2UO₃·2SiO₂·7H₂O | 3.8-3.9 | 2-3 |
Many books have been written about rocks and minerals. Some are listed below, and it is likely that your librarian will be able to suggest others.
Getting Acquainted With Minerals, by George L. English and David E. Jensen. McGraw-Hill Book Company, Inc., New York, N. Y. (second edition, 1958).
The Rock Book, by Carroll L. Fenton and Mildred A. Fenton. Doubleday & Company, Inc., Garden City, N. Y. (1940).
Mineral Collector’s Guide, by David E. Jensen. Ward’s Natural Science Establishment, Inc., Rochester, N. Y. (1953).
My Hobby is Collecting Rocks and Minerals, by David E. Jensen. Hart Book Company, New York, N. Y. (1955).
Rocks and Minerals, by Richard M. Pearl. Barnes & Noble, New York, N. Y. (1956).
1001 Questions Answered About the Mineral Kingdom, by Richard M. Pearl. Dodd, Mead & Company, New York, N. Y. (1959).
Rocks and Minerals, by Herbert S. Zim and Paul R. Schaffer. Simon and Schuster, Inc., New York, N.Y. (1957).
Economic Mineral Deposits, by Alan M. Bateman. John Wiley & Sons, Inc., New York, N. Y. (second edition, 1950).
A Textbook of Mineralogy, by Edward S. Dana, revised by William E. Ford. John Wiley & Sons, Inc., New York, N. Y. (fourth edition, 1932).
Industrial Minerals and Rocks (Nonmetallics Other Than Fuels), Joseph L. Gillson, Editor-in-Chief. The American Institute of Mining, Metallurgical, and Petroleum Engineers, New York, N. Y. (third edition, 1960).
Dana’s Manual of Mineralogy, revised by Cornelius S. Hurlbut, Jr. John Wiley & Sons, Inc., New York, N. Y. (seventeenth edition, 1959).
Mineralogy, by Edward H. Kraus, Walter F. Hunt, and Lewis S. Ramsdell. McGraw-Hill Book Company, Inc., New York, N. Y. (fifth edition, 1959).
Nonmetallic Minerals, by Raymond B. Ladoo and W. M. Meyers. McGraw-Hill Book Company, Inc., New York, N. Y. (second edition, 1951).
Rocks and Rock Minerals, by Louis V. Pirsson, revised by Adolph Knopf. John Wiley and Sons, Inc., New York, N. Y. (third edition, 1947).
A Field Guide to Rocks and Minerals, by Frederick H. Pough. Houghton Mifflin Company, Boston, Mass. (third edition, 1960).
Mineral Facts and Problems, by the Staff of the Bureau of Mines. U. S. Bureau of Mines Bulletin 585. U. S. Government Printing Office, Washington, D. C. (1960).
Entries marked with an asterisk are published by the Bureau of Economic Geology, The University of Texas, Austin. Those not out of print are distributed at nominal sale price, and a list of publications will be sent on request. These publications can be consulted at many public libraries and Chamber of Commerce offices.
*Report on the Pavitte Silver-Copper Prospect in Burnet County, Texas, by V. E. Barnes. Univ. Texas, Bureau Econ. Geol. Mineral Resource Survey Circ. 5 (1936).
*Report on the Sheridan Copper Prospect in Burnet County, Texas, by V. E. Barnes. Univ. Texas, Bur. Econ. Geol. Mineral Resource Survey Circ. 9 (1936).
*Building Stones of Central Texas, by V. E. Barnes, R. F. Dawson, and G. A. Parkinson. Univ. Texas Pub. 4246 (1947).
*Iron Ore in the Llano Region, Central Texas, by V. E. Barnes. Univ. Texas, Bur. Econ. Geol. Rept. Inves. No. 5 (1949).
*Utilization of Texas Serpentine, by V. E. Barnes, D. A. Shock, and W. A. Cunningham. Univ. Texas Pub. 5020 (1950).
*Lead Deposits in the Upper Cambrian of Central Texas, by V. E. Barnes. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 26 (1956).
*Mineral Resources of the Colorado River Industrial Development Association Area, by J. W. Dietrich and J. T. Lonsdale. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 37 (1958).
*Some Uranium Occurrences in West Texas, by D. H. Eargle. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 27 (1956).
*A Preliminary Report on the Stratigraphy of the Uranium-Bearing Rocks of the Karnes County Area, South-Central Texas, by D. H. Eargle and J. L. Snider. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 30 (1957).
The Brown Iron Ores of Eastern Texas, by E. B. Eckel. U. S. Geol. Survey Bull. 902 (1938).
*The Rustler Springs Sulphur Deposits as a Source of Fertilizer, by G. L. Evans. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 1 (1946).
Origin of the Gulf Coast Salt-Dome Sulphur Deposits, by Herbert W. Feely and J. Lawrence Kulp. Bull. Amer. Assoc. Petrol. Geol., vol. 41, pp. 1802-1853 (1957).
*Pegmatites of the Van Horn Mountains, Texas, by P. T. Flawn. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 9 (1951).
*The Hazel Copper-Silver Mine, Culberson County, Texas, by P. T. Flawn. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 16 (1952).
*Basement Rocks of Texas and Southeast New Mexico, by P. T. Flawn. Univ. Texas Pub. 5605 (1956).
*Texas Miners Boost Talc Output, by P. T. Flawn. Univ. Texas, Bureau Econ. Geol. Rept. Inves. No. 35 (1958).
*Geology and Mineral Deposits of Pre-Cambrian Rocks of the Van Horn Area, Texas, by P. B. King and P. T. Flawn. Univ. Texas Pub. 5301 (1953).
*Igneous Rocks of the Balcones Fault Region of Texas, by J. T. Lonsdale. Univ. Texas Bull. 2744 (1927).
Mineral Resources of the Llano-Burnet Region, Texas, with an Account of the Pre-Cambrian Geology, by Sidney Paige. U. S. Geol. Survey Bull. 450 (1911).
*Mineral Resources of the Texas Coastal Plain (Preliminary Report), by J. M. Perkins and J. T. Lonsdale. Univ. Texas, Bureau Econ. Geol. Mineral Resource Circ. 38 (1955).
Geology and Ore Deposits of the Shafter Mining District, Presidio County, Texas, by C. P. Ross. U. S. Geol. Survey Bull. 928-B (1943).
*The Geology of Texas, Vol. II, Structural and Economic Geology, by E. H. Sellards, C. L. Baker, and others. Univ. Texas Bull. 3401 (1935).
*Texas Mineral Resources, by E. H. Sellards and others. Univ. Texas Pub. 4301 (1946).
*Geological Resources of the Trinity River Tributary Area in Texas and Oklahoma, by H. B. Stenzel, A. E. Weissenborn, and others. Univ. Texas Pub. 4824 (1948).
Uranium at Palangana Salt Dome, Duval County, Texas, by A. D. Weeks and D. H. Eargle. In U. S. Geol. Survey Prof. Paper 400-B (1960).
Geology of the Quicksilver Deposits of the Terlingua District, Texas, by R. G. Yates and G. A. Thompson. U. S. Geol. Survey Prof. Paper 312 (1959).
Amorphous—without crystalline structure and therefore without regular form.
Balcones fault zone—a system of faults extending from north of Waco in McLennan County, through Travis and Bexar counties, to near Del Rio in Val Verde County (see p. 42).
Boulder—a large rock or mineral fragment that has a diameter greater than 256 millimeters (about 10 inches).
Breccia—a rock made up of sharp-cornered, cemented fragments with diameters greater than 2 millimeters (about ⁸/₁₀₀ of an inch).
Cambrian—the earliest period of the Paleozoic Era (see p. 3).
Cenozoic—the present era, one of the great divisions of geologic time (see p. 3). This era began about 63 million years ago.
Clastic—made up of broken fragments of rocks or minerals.
Cleavage—occurs when minerals split along smooth flat surfaces that are parallel to possible crystal faces. These planes as well as crystal faces are controlled by the crystal lattice or atomic structures of the minerals.
Cleavage fragment—a mineral specimen that has been broken along its planes of cleavage.
Cobble—a rock or mineral fragment that has a diameter between 64 and 256 millimeters (about 2½ and 10 inches).
Conchoidal—a curved fracture surface shaped like the inside of a shell or spoon.
Conglomerate—a rock composed of cemented, rounded rock or mineral fragments, most of which are of gravel size.
Cretaceous—the third and latest period of the Mesozoic Era (see p. 3).
Cryptocrystalline—made up of tiny crystalline particles that are too small to be distinguished even under high magnification.
Crystalline—having a definite, orderly internal structure.
Cube—a solid that has six equal, square sides.
Dodecahedron—a solid that has twelve plane, four-sided faces.
Element—a basic building block of all matter, which cannot be separated into different substances by ordinary chemical means.
Eocene—the second epoch of the Tertiary Period (see p. 3).
Epoch—a unit of geologic time that is a subdivision of a period.
Era—a major division of geologic time, which consists of several periods.
Extrusive rocks—igneous rocks formed from magma that was extruded on the earth’s surface.
Fault—a break in the rocks or strata of the earth’s crust along which movement or slippage has taken place.
Fluid—a substance made up of particles that can move freely about; it can be a liquid or a gas.
Formation—rocks or strata that are recognized and mapped as a unit.
Fracture—the kind of surface obtained if a mineral is broken in a different direction from that of the cleavage or parting. Commonly, fracture surfaces are rough, uneven, or curved, whereas cleavage surfaces are smooth.
Geologic map (areal)—shows the extent and distribution of formations exposed at the earth’s surface.
Granular—the texture of a rock or mineral that is made up of visible grains. If all the grains are about the same size, the term equigranular is used.
Granule—a rock or mineral fragment that has a diameter of from 2 to 4 millimeters (about ⁸/₁₀₀ to ¹⁵/₁₀₀ of an inch).
Gravel—uncemented rock or mineral fragments that have diameters greater than 2 millimeters (about ⁸/₁₀₀ of an inch).
Gulf Coastal Plain—an area that extends, in Texas, from the Gulf of Mexico to the Balcones fault zone and in which Quaternary, Tertiary, and Upper Cretaceous strata crop out at the surface (see p. 42).
High Plains—an area in northwest Texas extending from the Pecos River valley north to the Oklahoma-Texas boundary (see p. 42).
Igneous rocks—rocks formed by the cooling and hardening of hot, molten rock material.
Intrusive rocks—igneous rocks that have formed below the surface of the earth.
Lava—molten rock material that has poured out onto the earth’s surface from volcanoes; also the rock that is formed after the molten material has cooled and hardened.
Llano uplift—an area in central Texas where Precambrian and early Paleozoic rocks occur at the earth’s surface (see p. 42).
Magma—hot, molten rock material from which igneous rocks form.
Massive—in a mass, without a regular or complete form.
Mesozoic—an era, one of the great divisions of geologic time (see p. 3). This era began about 230 million years ago and lasted until about 63 million years ago.
Metamorphic rock—rock formed from igneous or sedimentary rocks that are altered by heat, pressure, and fluids below the earth’s surface.
Miocene—the fourth epoch of the Tertiary Period (see p. 3).
Mississippian—the fifth period of the Paleozoic Era (see p. 3).
Nodule—a small, rounded mass or lump.
Octahedron—a solid that has eight triangular faces.
Opaque—no light can pass through.
Ordovician—the second period of the Paleozoic Era (see p. 3).
Paleozoic—an era, one of the great divisions of geologic time (see p. 3). This era began at the end of Precambrian time and lasted until about 230 million years ago.
Parting—occurs when a mineral breaks along a flat surface that is not a true cleavage plane.
Pebble—a rock or mineral fragment that has a diameter between 4 and 64 millimeters (about ¹⁵/₁₀₀ and 2½ inches).
Pennsylvanian—the sixth period of the Paleozoic Era (see p. 3).
Period—a unit of geologic time, a subdivision of an era.
Permian—the last period of the Paleozoic Era (see p. 3).
Physiographic outline map—shows location of natural regions (p. 42).
Playa lake—a temporary shallow lake in a nearly level, closed basin, which has no drainage outlet.
Pleistocene—the first epoch of the Quaternary Period (see p. 3).
Pliocene—the last epoch of the Tertiary Period (see p. 3).
Precambrian—comprises the Early and the Late Precambrian Eras, the earliest great divisions of geologic time. Rocks that formed more than 600 million years ago are known as Precambrian rocks.
Pyritohedron—a solid that has twelve 5-sided faces.
Quaternary—the present period of geologic time; the second period of the Cenozoic Era (see p. 3).
Recent—the present epoch of geologic time; the second epoch of the Quaternary Period (see p. 3).
Sectile—describes material, such as soap, that can be cut smoothly with a knife.
Sediments—material deposited by water, wind, or ice on the earth’s surface.
Sedimentary rocks—rocks made up of sediments.
Series—a subdivision of a system that includes all rocks formed during an epoch.
Specific gravity—the ratio of the weight of a substance to the weight of an equal volume of water.
Streak—the color of the powder of a mineral.
System—all rocks formed during a period.
Tertiary—the first period of the Cenozoic Era (see p. 3).
Translucent—light will pass through, but objects cannot be seen.
Transparent—light will pass through, and objects can be seen.
Trans-Pecos—area of Texas located west of the Pecos River (see p. 42).
Volcanic rocks—igneous rocks that have formed on the earth’s surface; extrusive rocks.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z