BUREAU OF ECONOMIC GEOLOGY The University of Texas at Austin Austin, Texas 78712 JOHN T. LONSDALE, _Director_ Report of Investigations—No. 42 Texas Gemstones By Elbert A. King, Jr. February 1961 _Second Printing—February 1963 Third Printing—September 1972 Fourth Printing—March 1983 Fifth Printing—August 1991_ Contents Page Introduction 5 Properties of gemstones 5 Crystals 7 Cutting and polishing of gemstones 10 Cabochon gems 10 Faceted gems 13 Tumbled gems 17 Texas gemstones 18 Amber 18 Augite 18 Beryl 18 Celestite 19 Diamond 19 Epidote 19 Fluorite 20 Fossil wood 20 Gadolinite 21 Garnet 22 Jet 22 Labradorite 23 Microcline 23 Obsidian 24 Opal 24 Pearl 24 Quartz 25 Crystalline varieties 25 Amethyst 25 Citrine 25 Rock crystal 26 Rose quartz 26 Smoky quartz 26 Cryptocrystalline varieties 27