Chalcedony 27 Agate 27 Agatized wood 27 Carnelian 27 Jasper 27 Sanidine 28 Spinel 28 Tektite (bediasite) 28 Topaz 29 Tourmaline 30 Turquoise 31 Glossary 32 Selected references 34 Index 41 Illustrations Figures— Page 1. Typical crystal form of three common Texas gemstones 9 2. Variations of the cabochon cut 10 3. Diamond saw 11 4. Cabochon properly attached to dop-stick 12 5. Cabochons at various stages of cutting and polishing 12 6. Nomenclature of the standard American brilliant cut 13 7. Facet table 14 8. Grinding the table facet on a rough stone 15 9. Stone dopped to table facet 15 10. Preformed stone dopped to table facet 16 11. Proper sequence of cutting of the pavilion facets 16 12. Proper placing of pavilion girdle facets 17 13. Proper sequence of cutting of crown facets 17 14. Common crystal form of Travis County celestite 19 15. Common crystal form of fluorite 20 16. Crystal faces on microcline specimen shown in Plate III 23 17. Common crystal form of spinel 28 18. Crystal faces on topaz crystal shown in Plate V 29 19. Cross section through irregularly colored stone 30 20. Common crystal form of Llano County tourmaline 31