J jasper: [27]-28 Jeff Davis County: [26], [27], [28], [31] jet: [22]
K Kinney County: [28]
L labradorite: [23], [36] Lake Buchanan: [21] Lampasas County: [19] lap plate: [13] Lavaca County: [29] Lee County: [20], [29] lignite: [22] Live Oak County: [21] Llano County: [18], [19], [20], [21], [22], [23], [25], [26], [30], [31], [40] Llano River: [25] luster: [5]
M Madeira topaz: [29] Mason County: [20], [22], [23], [26], [29], [30], [39], [40] Massachusetts: [29] Maverick County: [18] microcline: [20], [21], [23]-24, [29], [37] Mohs scale of hardness: [6] moonstone: [28] Mount Bonnell: [19] muscovite: [23]
N natural glass: [18], [24], [28] Needle Peak, Presidio County: [27] nivenite: [21] Nolan County: [19] Nueces River: [25]
O obsidian: [24], [29] Oklahoma: [29] opal: [20], [24] opalized wood: [35] orbicular jasper: [28] ounce: [7]
P Packsaddle Mountain: [23] Packsaddle schist: [30] palm wood: [21], [35] Palo Duro Canyon: [21] pavilion: [13], [16] facets: [16] girdle facets: [16], [17] pearl: [24]-25 pegmatites and/or pegmatite dikes: [18], [20], [21], [22], [23], [26], [29], [39] petrified wood: [26] phantom crystals: [26] pistacite: [20] pleochroism: [5] point: [7] polishing: [17] lap: [13], [16] preformed stone: [16] preforming: [15] Presidio County: [20], [22], [24], [25], [26], [27], [28] properties of gemstones: [5]-7
Q quartz: [20], [21], [23], [25]-28, [29], [30] smoky: [38]
R radioactive elements: [22] radioactivity of gadolinite: [21] rarity: [6] Reeves County: [26], [27] Rio Grande: [25] gravels of: [21], [27], [38] Valley: [27] rock crystal: [26] rose quartz: [26]
S Sabine River: [25] sanding: [12] sanidine: [28] sawing: [10] scheelite: [20] schorl: [30] size: [7] “skill” facets: [16] “slab” of gem materials: [11] Smithsonian Institution: [21] smoky quartz: [23], [26], [37] smoky topaz: [29] Spanish topaz: [29] specific gravity: [7] spinel: [18], [28] star facets: [17] step cut: [15] streak: [6] synthetic gems: [7]