Agate Geode
Chalcedony (SiO2 - Silicon Dioxide)
Category
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Agate Geode
Chalcedony (SiO2 - Silicon Dioxide)
Quartzite (River Cobble)
Quartzite (SiO2)
Specular Hematite with Quartz and Limonite
Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)
Milky Quartz with Iron Staining
Quartz (Silicon Dioxide, SiO2)
Banded Chert (Flint)
Cryptocrystalline Quartz (SiO2)
Red Garnet
Pyrope-Almandine series (Mg3Al2(SiO4)3 to Fe3Al2(SiO4)3)
Red Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Amethyst
Amethyst (Silicon Dioxide containing trace Iron impurities, SiO2)
Schist
Mica Schist
Chert (and/or Chalcedony)
Silicon dioxide (SiO2)
Jasper
Silicon Dioxide (SiO2) with iron and magnesium inclusions
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
Limonite
Limonite (Hydrated iron(III) oxide-hydroxide) FeO(OH)·nH2O
Opalite
Opalescent Glass (SiO2 + coloring agents)
Sandstone (with differential weathering)
Arenite / Quartz Sandstone (SiO2)
Magnetite (Iron Ore)
Magnetite (Fe3O4)
Optical Calcite (Iceland Spar)
Calcite (Calcium Carbonate, CaCO3)
Chalcedony (Agate/Carnelian variant)
Silicon Dioxide (SiO2)
Pyrite
Iron Disulfide (FeS2)
Rhodonite
Rhodonite (Manganese silicate), (Mn,Fe,Mg,Ca)SiO3
Muscovite Schist
Mica Schist (KAl2(AlSi3O10)(OH)2)
Amethyst (Rough Quartz)
Silicon Dioxide (SiO2) with iron impurities
Diamond (set in jewelry)
Diamond (Carbon, C)
Garnet-bearing Schist
Almandine Garnet (Fe3Al2(SiO4)3) in Mica Schist
Chert (Flint variety)
Chert (SiO2)
Tektite (Indochinite)
Tektite (impactite), primarily high-silica glass (SiO2)
Petrified Wood
Silicified Wood (primarily SiO2)
Chert (often called Flint when dark or worked)
Cryptocrystalline silica (SiO2)
Jasper
Silicon dioxide (SiO2)
Jasper
Silicon Dioxide (SiO2) - Opaque Chalcedony
Chert (Nodule)
Microcrystalline Quartz (SiO2)
Slate
Foliated Metamorphic Rock (composed primarily of silica and alumina with iron and magnesium)
Moss Agate Geode Sphere
Silicon Dioxide (SiO2) - Chalcedony with Chlorite or Manganese inclusions
Banded Calcite (often sold as Caribbean Calcite or Pink Calcite)
Calcium Carbonate (CaCO3)
Green Fluorite
Fluorite (Calcium Fluoride - CaF2)
Jasper
Agate/Jasper (Microcrystalline Quartz, SiO2)
Green Aventurine
Silicon Dioxide (SiO2) with inclusions
Gold
Gold (Au)
Biotite Schist
Biotite Schist
Mosasaur Tooth Fossil
Mosasaurid vertebrate fossil (Hydroxyapatite)
Quartz Pebble
Silicon Dioxide (SiO2)
Golden Healer Quartz
Ferruginous Quartz (SiO2 with Fe2O3 inclusions)