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 Ca₂Mg₅Si₈O₂₂(OH)₂ 3.0-3.3 1-2½
asbestos
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, 2.8-3.2 2½-3
Fe)₃AlSi₃O₁₀(OH)₂
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 3.0-3.25 7-7½
boron and aluminum
Uranophane CaO·2UO₃·2SiO₂·7H₂O 3.8-3.9 2-3