Gneiss (specifically a Granitic Gneiss specimen)
Gneiss (high-grade metamorphic rock primarily composed of Quartz, Feldspar, and Biotite/Amphibole)
Category
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Gneiss (specifically a Granitic Gneiss specimen)
Gneiss (high-grade metamorphic rock primarily composed of Quartz, Feldspar, and Biotite/Amphibole)
Anthracite Coal
Anthracite (Carbon based)
Basalt
Basalt (Mafic Extrusive Igneous Rock)
Glass
Amorphous Silicon Dioxide (SiO2)
Ferruginous Quartz
Quartz (Silicon Dioxide, SiO2) with Iron Oxides
Fluorite (Rainbow Fluorite)
Fluorite (Calcium Fluoride, CaF2)
Fossiliferous Limestone (Coquina)
Biogenic Limestone (Calcium Carbonate, CaCO3)
Schist (Biotite/Mica Schist)
Medium-grade regional metamorphic rock (rich in Phyllosilicates)
Green Aventurine
Aventurine Quartz (SiO2 with Fuchsite inclusions)
Clear Quartz
Silicon Dioxide (SiO2)
Shale with Plant Fossils / Carbonaceous Shale
Laminated Mudrock (Siliciclastic)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Dendritic Jasper (River Stone)
Silicon Dioxide (SiO2) with Manganese/Iron Oxide inclusions
Chert (Jasper/Agate variety)
Silicon Dioxide (SiO2)
Chert (Yellow Jasper/Quartzite Pebble)
Microcrystalline Silicon Dioxide (SiO2)
Muscovite Mica (on Quartz Matrix)
Muscovite - KAl2(AlSi3O10)(OH)2
Milky Quartz (Water-worn Pebble)
Silicon Dioxide (SiO2)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Green Aventurine
Aventurine (a variety of Quartz, SiO2 with fuchsite inclusions)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Quartz (Drusy/Crystalline variety)
Silicon Dioxide (SiO2)
Green Fluorite
Calcium Fluoride (CaF2)
Blue Sapphire
Corundum (Al2O3 with trace Titanium/Iron)
Pyrite
Iron Sulfide (FeS2)
Chert (River Stone/Pebble)
Chert (SiO2)
Ferruginous Sandstone
Arenite with Iron-oxide cement
Banded Iron Formation (BIF)
Banded Iron Formation
Chert (Nodule)
Microcrystalline Quartz (SiO2)
Garnet Schist
Garnetiferous Micaceous Schist
Greyling Sandstone / Greywacke
Lithic Wacke (SiO2 + diverse mineral fragments)
Chert (Jasper)
Silicon Dioxide (SiO2) with impurities
Schist
Mica Schist
Stichtite in Serpentine (Atlantisite)
Mg6Cr2CO3(OH)16·4H2O (Stichtite) within Mg3Si2O5(OH)4 (Serpentine)
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Quartzite Pebbles
Quartzite (SiO2)
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Greenstone / Chert
Cryptocrystalline Quartz (SiO2) or Altered Basalt
Sandstone
Arenite (general term for sandstone)
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
Shiva Lingam
Cryptocrystalline Quartz (Jasproid/Jasper)
Mica Schist
Mica Schist (Complex Silicate Rock)