Chert (Arrowhead/Projectile Point)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Category
Mineraloid (Anthropogenic)
Browse mineraloid (anthropogenic) specimens identified by the Rock Identifier community.
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Chert (Arrowhead/Projectile Point)
Cryptocrystalline Quartz (SiO2)
sedimentary
Obsidian Arrowhead
Obsidian (Volcanic Glass)
igneous
Painted River Rock
Anthropogenic-modified Siliciclastic Sedimentary Rock
Sedimentary
Slag
Glassy silicate byproduct (anthropogenic material)
industrial byproduct
Slag
Anthropogenic Vitrophyre (Iron or Smelting Slag)
Mineral-like byproduct
Iron Slag (Industrial Byproduct)
Anthropogenic Vitrification Product/Ferrous Slag
Mineral-like Industrial Smelting Waste
Ferro-slag (Leland Blue/Slag Glass)
Anthropogenic Vitreous Silica (Industrial Slag)
igneous
Sea Glass
Amorphous Silica (Anthropogenic glass) - SiO2
mineral
Sandstone (likely Fossilized Wood or Concrete Simulacrum)
Arenite / Silicified Wood / Anthropogenic Concrete
sedimentary
Black Obsidian
Volcanic glass
igneous
Obsidian
Volcanic Glass
igneous
Obsidian
Volcanic Glass (Amorphous silicon dioxide with impurities)
igneous
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Fulgurite
Fulgurite (Lechatelierite)
metamorphic
Black Obsidian
Volcanic Glass (SiO2 + impurities)
Igneous
Gold Sheen Obsidian
Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)
igneous
Painted River Rock
Artificially Coated Sedimentary Rock
sedimentary
Titanium Aura Quartz (Bismuth-coated Druzy)
Silicon Dioxide (SiO2) with Titanium/Metal vapor coating
mineral
Conglomerate (Asphaltic/Anthropogenic)
Clastic sedimentary rock / Bituminous mixture
sedimentary
Anthracite Coal
Anthracite (Carbon-rich mineraloid)
metamorphic
Amber
Succinite (Organic Mineraloid) - C10H16O
mineral
Chert (Arrowhead variety)
Chert (SiO2)
sedimentary
Basalt
Basalt (Mafic Extrusive Igneous Rock)
igneous
Possible tektite or iron-rich slag-like natural specimen
Uncertain; possibly natural glass (tektite) or magnetite-rich rock
mineral
Obsidian
Volcanic glass
igneous
Limonite (Ironstone)
Limonite (mixture of hydrated iron oxides, primarily Goethite α-FeO(OH))
mineral
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
White Opal
Hydrated Silica (SiO2·nH2O)
mineral
Possible tektite or volcanic glass specimen
Natural silica glass; composition commonly near SiO₂, but exact identification requires chemical testing
mineral
Chert (Arrowhead Debitage or Flake)
Microcrystalline silica (SiO2)
sedimentary
Polished mahogany obsidian (probable)
Volcanic glass; chiefly rhyolitic silica-rich glass (SiO₂), compositionally near rhyolite
igneous
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Obsidian
Volcanic Glass (Amorphous SiO2)
igneous
Obsidian
Volcanic Glass (SiO2 rich)
igneous
Fulgurite
Fulgurite (Lechatelierite-rich fused silica)
mineraloid / sedimentary (secondary formation)
Limonite (Iron Ore)
Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)
Mineral
Pearl
Organic Mineraloid (CaCO3 + Conchiolin)
mineral
Abalone Shell (Nacre)
Aragonite (CaCO3) - Biogenic Mineral
mineral
Greenstone Celt (Polished Stone Axe)
Metamorphosed mafic rock (often Basalt or Diabase)
metamorphic
Obsidian
Volcanic Glass (70% or more SiO2)
igneous
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Igneous