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
[Dolomite] CaMg(CO₃)₂ 2.85 3½-4
[Feldspar] (see Albite, [Microcline], [Orthoclase])
[Fluorite] CaF₂ 3.18 4
[Galena] PbS 7.4-7.6
[Garnet] (see Almandite, [Grossularite])
[Gold] Au 15.0-19.3 2½-3
[Graphite] C 2.2 1-2
Grossularite Ca₃Al₂(SiO₄)₃ 3.53
[Gypsum] CaSO₄·2H₂O 2.32 2
[Halite] NaCl 2.16
[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
[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

BOOKS ABOUT ROCKS AND MINERALS

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.

Nontechnical Books for Beginners

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).