Quartzite
Quartzite (SiO2)
metamorphic
Agate Geode
Silicon Dioxide (SiO2) - Microcrystalline Quartz
mineral
Sandstone Concretion
Ferruginous Sandstone Concretion (Primarily SiO2 with Iron Oxide cement)
sedimentary
Sandstone (Ferruginous)
Arenite (Fe-rich)
sedimentary
Quartzite Pebble
Recrystallized Quartz (SiO2)
metamorphic
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Sandstone Concretion
Clastic Sedimentary Concretion (typically Quartz/Silica with Iron Oxide)
sedimentary
Quartz (Milky/Yellowish Pebble)
Silicon Dioxide (SiO2)
mineral
Quartzite (River Stone)
Quartzite (SiO2)
metamorphic
Quartz (River Stone)
Silicon Dioxide (SiO2)
mineral
Sandstone with Calcite Vein
Clastic sedimentary rock (primarily SiO2) with Calcium Carbonate (CaCO3) infilling
sedimentary
Chert (Nodular Chert)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Porphyritic Rhyolite
Rhyolite (Porphyritic texture)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartz Geode (Cracked Open)
Quartz (Silicon Dioxide - SiO2)
mineral
Quartz (Milky/Iron-stained)
Silicon Dioxide (SiO2)
mineral
Red Jasper
Jasper (Silicate mineral - SiO2)
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Sandstone Concretion
Arenaceous concretion (primarily SiO2 with Fe2O3 staining)
sedimentary
Sandstone Concretion with Fossil Wood
Ferruginous Sandstone Concretion (SiO2 with Fe2O3 cement)
sedimentary
Carnelian Agate
Silicon dioxide (SiO2) - variety of Chalcedony
mineral
Bauxite
Bauxite (Mixture of Al(OH)3, AlO(OH), and Fe2O3)
sedimentary
Mica Schist
Muscovite Schist (KAl2(AlSi3O10)(OH)2)
metamorphic
Graphite
Graphite (Native Carbon, C)
metamorphic
Specular Hematite (Specularite)
Hematite (Alpha-Fe2O3)
mineral
Granitic Pegmatite with Tourmaline and Sphalerite
Pegmatite containing Schorl (NaFe3Al6(BO3)3Si6O18(OH)4) and Sphalerite ((Zn,Fe)S)
igneous
Rose Quartz
Silicon Dioxide (SiO2) with trace Titanium, Manganese, or Iron
mineral
Pink Tourmaline (Rubellite) in Lepidolite
Elbaite (Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)4) in Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)
igneous
Quartzite
Quartzite (SiO2)
metamorphic
Chert (variations include Flint/Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Anthracite Coal
Anthracite
metamorphic
Quartz (Milky or White Quartz)
Silicon Dioxide (SiO2)
mineral
Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
metamorphic
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Smoky Quartz
SiO2 (Silicon Dioxide)
mineral
Smoky Quartz
Silicon Dioxide (SiO2) with aluminum impurities
mineral
Fuchsite (Green Muscovite in Quartz)
Chromium-rich Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)
metamorphic
Malachite
Copper(II) carbonate hydroxide, Cu2CO3(OH)2
mineral
Optical Calcite (Iceland Spar)
Calcite (Calcium Carbonate, CaCO3)
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Pink Quartzite
Quartzite (primarily SiO2)
metamorphic