G gabbro: 87 gneiss: 59 Gaines County: 83 galena: 17, 26, 57, 89, 90 argentiferous: 57, 90 Galveston County: 91 Gamble prospect: 67 gamma rays: 96 garnet: 31, 33, 34, 37, 58, 85, 87 Garza County: 97 Geiger counter: 96 gemstones: 56, 58, 77, 82, 94, 95 geode: 19, 46, 49, 82 geologic map: 4, 5 geologic time scale: 2, 3 geologists: 2 geology: 2 Gillespie County: 44, 45, 55, 58, 59, 60, 61, 65, 76, 80, 82, 83, 87, 88, 94 glass, natural: 9, 77, 85, 97 glass sand: 85-86 glauconite: 70, 73 glossary: 102-103 gneiss: 13, 41, 55, 56, 59, 67, 72, 73, 74, 76, 81, 87, 93, 97 conglomerate: 59 gabbro: 59 granite: 59 hornblende: 59 mica: 59 goethite: 70 gold: 26, 51, 59, 80, 90 fool’s: 53, 80 Gonzales County: 52, 84, 97 Grand Saline salt dome: 66 granite: 2, 8, 9, 13, 41, 48, 55, 56, 59, 61, 72, 76, 79, 81, 85, 87, 94, 95 gneiss: 59 opaline: 72 Granite Mountain: 62 Granite Shoals Lake: 56 granules: 85 graphite: 26, 27, 62, 75 schist: 63, 87 gravel: 12, 41, 91 green copper carbonate: 53 greensands: 70 Grit: 94 grossularite: 58 group: 6 Guadalupe Mountains, Peak: 1 Gulf Coast: 91 Gulf Coastal Plain: 20, 42, 43, 46, 51, 52, 58, 60, 65, 66, 78, 83, 84, 86, 87, 92, 97, 98 Gulf salt dome: 91 Gyp Hill salt dome: 64 gypsite: 65 gypsum: 28, 29, 30, 32, 36, 37, 43, 63, 70, 85, 91 alabaster: 65 fibrous gypsum: 64, 65 rock gypsum: 40, 65 rosettes: 63, 64 satin spar: 64 selenite: 63, 64, 76 H halite: 28, 32, 34, 35, 36, 38, 40, 43, 65, 91 hand lens: 22 Hardeman County: 52, 58, 64, 65 hardness of minerals: 16, 99 Harris, Bill M.: vii Harris, John S.: vii Harris County: 65, 66 Hartley County: 79 Hays County: 45 Hazel Formation: 52 Hazel mine: 52, 53, 90 Heath mine: 60 hematite: 26, 27, 36, 66, 75, 84, 86 specular: 67 Henderson County: 70 High Island salt dome: 91 High Plains: 42, 46, 51, 65, 66, 78, 79, 83, 87, 97, 98 Hockley salt dome: 65, 66 hollandite: 26, 27, 28, 73, 74 Honey Creek area: 87 hornblende: 8, 59, 61 gneiss: 59 schist: 87 horn silver: 90 Hoskins Mound salt dome: 91 Houston: 70 Howard County: 45, 60 Hudspeth County: 45, 52, 53, 55, 56, 57, 58, 59, 60, 62, 65, 66, 67, 75, 79, 82, 83, 90, 93, 95 Humphreys, Alan: vii Hutchinson County: 66 hyalite: 78 hydrochloric acid (_see also_ chemical tests): 18, 22 I identification charts: 24 igneous rocks, definition of: 9 intrusive igneous rocks, definition of: 9 Irion County: 60 iron: 59, 66, 67, 69, 70, 72, 73 Iron Mountain: 73