P Pacific [33], [41] Paint ore [58] Paleontology [71] Paris [33] Petrified wood [35], [43], [69] Petroleum [71] Phelps County [26], [27] Phenocrysts [46] Pilot Knob [56] Plagioclase feldspar [44], [49], [74] Plaster of paris [63] Plastic fire clay [26] Polish on marble and granite [16] Pop-corn flint fire clay [26] Porphyry [31], [40], [44], [45], [53], [73] Porphyry, chemical composition [40] Potosi [37] Pyrite [14], [49], [51], [52], [53], [57], [58], [63], [66], [74] [Pyroxene] [49], [74]
Q Quarry [14] Quartz [30], [38], [39], [40], [41], [45], [49], [54], [65], [68], [74] Quartzite [32], [55], [73]
R Radioactivity [66] Reynolds County [58] Rhyolite, rhyolite porphyry [45], [71], [73] Ripple marks [33] Rock crystal [42] Rock, definition [5], [73] Rock wool [13] Rose quartz [42] Rosin jack zinc ore [60] Rosin spar zinc ore [60] Ruby jack zinc ore [60]
S Sampling rock or ore [15], [59] Sand [14], [30] Sandstone [30], [41], [43], [53], [55], [66], [73] Sandstone, chemical composition [23] Satinspar gypsum [63] Sedimentary rock [72], [73] Selenite gypsum [63] Shale [19], [20], [24], [50], [53], [55], [66], [73], [74] Shale, chemical composition [23] Shannon County [58] Silica [35], [43], [66] Silver [59], [65] Silver Mines [65] Six-sided crystals [16], [41] Slate [21], [50], [55] Soapstone [21] Soil sweetening [13], [14], [20] Sphalerite [60], [74] “Sponge” limestone rock [13] Stalactites [16] Stalagmites [16] State Geologist, Geological Survey [6], [24], [51], [59] St. Francois County [39], [45] St. Louis County [26] St. Peter sandstone formation [41] Ste. Genevieve [65] Streak of mineral [6], [56] Sulphur [51] Sulphuric acid [10], [53], [63]
T Texas County [62] Tiff [16], [61] Travertine [16], [73] Tripoli [37], [43] Tyuyamunite [65], [74]
U University of Missouri Geology Department [6] Uranium Minerals [65], [66]
V Vanadium [66] Vernon County [32]
W Warren County [27] Warrensburg [33] Washington County [62] Weathered chert [19], [35], [36], [37] Widmanstatten figure [64]
Z Zinc ore [60]