TEXAS GEMSTONES Amber _Composition_: fossil resin. _Crystal system_: amorphous. _Hardness_: about 2.0 to 2.5. _Specific gravity_: variable, from 1.05 to 1.10. _Luster_: resinous. _Color_: brown, yellow, red, orange, and white. _Streak_: white to yellowish to gray. _Cleavage_: none. _Fracture_: conchoidal. _Tenacity_: brittle. _Diaphaneity_: transparent to translucent. _Refractive index_: variable, about 1.54. Burns with a sweet, piney odor. Rich brown to yellowish amber has been found near Eagle Pass, Maverick County, in Cretaceous coal and on Terlingua Creek, Brewster County. Although much of this material is translucent and the quality suitable for lapidary purposes, the pieces are seldom more than a fraction of an inch in diameter. Occasional finds of poor quality brownish amber have been reported from the Tertiary formations of the Gulf Coastal Plain, but thus far no gem quality material has been found. The softness of amber limits its use to brooches, necklaces, and other jewelry that is relatively safe from abrasion. Augite _Composition_: CaMgSi₂O₄; may also contain iron, aluminum, and sometimes titanium. _Crystal system_: monoclinic. _Hardness_: 5 to 6. _Specific gravity_: 3.2 to 3.6. _Luster_: vitreous to dull. _Color_: dark greenish brown and greenish black. _Streak_: light grayish green. _Cleavage_: two directions, poor. _Fracture_: conchoidal to uneven. _Tenacity_: brittle. _Diaphaneity_: opaque to translucent. _Refractive index_: variable, about 1.60 to 1.71. Augite of gem quality occurs near Eagle Flat, Hudspeth County, Texas. Although this material is very dark greenish brown and not commonly thought of as a gemstone, lapidaries have used it to fashion black faceted stones and cabochons that resemble obsidian. Most of the augite occurs as loose pieces and crystal fragments that have weathered out of nearby igneous rocks; the augite can also be found in situ in the igneous rocks. Specimens and pieces of cutting quality 1 inch in diameter are common, and fragments over 2 inches in diameter have been found. The augite is associated with black spinel and some dark gray to black pieces of natural glass. Although the faceted and cabochon-cut stones are not particularly attractive, some of the larger pieces of augite might be utilized for carving. Beryl _Composition_: Be₃Al₂(SiO)₆. _Crystal system_: hexagonal. _Hardness_: 7.5 to 8.0. _Specific gravity_: 2.63 to 2.80. _Luster_: vitreous. _Color_: pale blue, blue, green, yellow, brownish, pink, and colorless. _Streak_: white. _Cleavage_: one direction, very imperfect. _Fracture_: conchoidal to uneven. _Tenacity_: brittle. _Diaphaneity_: transparent to subtranslucent. _Refractive index_: 1.56 to 1.60. _Dispersion_: low.