Diamond (Heart Cut)
Carbon (C)
gemstone
Category
Not A Geological Specimen
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Basalt with Quartz Veining
Basalt (Mafic Extrusive Igneous Rock) with SiO2 (Silicon Dioxide) veins
igneous
Quartz (Druzy) in host rock
SiO₂ (Silicon Dioxide) as Quartz, with unspecified host rock components (likely silicates and iron oxides)
Mineral
Quartz Druzy (on Matrix)
Silicon Dioxide (SiO2)
mineral
Lepidolite
Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)
mineral
Smoky Quartz and Feldspar Pegmatite
Granitic Pegmatite (chiefly SiO2 and KAlSi3O8)
igneous
Granite
Phaneritic Igneous Rock (composed primarily of Quartz, Feldspar, and Mica)
igneous
Sandstone with Quartz Veining
Arenite with SiO2 veins
sedimentary
Quartz (Water-worn pebble)
Silicon Dioxide (SiO2)
mineral
Quartz Pebble (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Petrified Wood
Silicified Wood (primarily SiO2)
fossil
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Ferruginous Sandstone (with ripple marks)
Arenite with Iron-Oxide (Fe2O3) cement
sedimentary
Pyrite Cubes in Matrix
Iron Disulfide (FeS2) in Host Matrix
mineral side rock
Granite Cobble
Granite (Phaneritic igneous rock)
igneous
Sandstone (Quartz-rich)
Sandstone (SiO2 dominated)
sedimentary
Quartz (Common or Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Granite
Phaneritic Plutonic Felsic Rock (SiO2 > 69%)
igneous
Chert (Chalcedony/Agate)
Microcrystalline Quartz (SiO2)
sedimentary
Quartz (Chert/Chalcedony Variety)
Silicon Dioxide (SiO2)
mineral
Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Pyrite
Iron Disulfide (FeS2)
mineral
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Quartz (Clear Quartz)
Silicon Dioxide (SiO2)
mineral
Carnelian Agate
Silicon Dioxide (SiO2) - Variety of Chalcedony
mineral
Quartz Geode Fragment
Crystalline Silicon Dioxide (SiO2)
mineral
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
mineral
Alkali Feldspar Granite
Alkali Feldspar Granite (KAlSi3O8)
igneous
Chert (and Fossiliferous Chert)
Silicon Dioxide (SiO2)
sedimentary
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
sedimentary
Fairy Stone (Staurolite Twin)
Staurolite (Fe,Mg,Zn)2Al9Si4O22(OH)2
metamorphic
Petrified Wood
Silicified Wood (SiO2)
mineral
Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Chert (Chert / Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chrysocolla
Hydrated copper phyllosilicate mineral (Cu,Al)2H2Si2O5(OH)4·n(H2O)
mineral
Banded Sandstone (Liesegang Rings)
Sedimentary sandstone with Iron oxide precipitates
sedimentary
Basalt
Extrusive mafic rock (Basalt)
igneous
Banded Agate
Chalcedony (Silicon Dioxide, SiO2)
mineral
Pink Coral
Corallium rubrum (Calcium Carbonate, CaCO3)
mineral
Granite Cobble
Phaneritic plutonic rock (dominated by Quartz, Feldspar, and Mica)
igneous
Milky Quartz with Iron Inclusions
Quartz (Silicon Dioxide, SiO2)
mineral