Obsidian / Chert (Arrowhead Artifact)
Obsidian (volcanic glass, SiO2 with impurities)
igneous
Category
Industrial Byproduct (Often Mistaken For Obsidian Or Mineral)
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Potassium-Rich Silicate Clay (inferred from biological context)
Phyllosilicate group (likely Illite or Smectite within surrounding soil substrate)
mineral
Basalt with Secondary Mineralization (Likely Zeolites or Calcite)
Aphanitic mafic volcanic rock with secondary mineral inclusions (e.g., CaAl2Si3O10·3H2O for Scolecite)
igneous
Snowflake Obsidian
Volcanic glass containing Cristobalite (SiO2)
igneous
Quartz vein in metamorphic rock
Crystalline Silicon Dioxide (SiO2) in Host Rock
metamorphic
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
igneous
Pegmatite
Coarse-grained Igneous Rock (Granitic Pegmatite)
igneous
Quartz with Iron Staining
Silicon Dioxide (SiO2) with Ferruginous Oxides
mineral
Ironstone (with Limonite/Goethite)
Ferruginous Sedimentary Rock (contains Limonite FeO(OH)·nH2O and Hematite Fe2O3)
sedimentary
Granitic Pegmatite with Schorl Tourmaline
Granitic Pegmatite (Schorl: NaFe3Al6(BO3)3Si6O18(OH)4)
igneous
Milky Quartz with Chlorite inclusions
Silicon Dioxide (SiO2) with Chlorite group minerals
mineral
Apache Tear (Obsidian)
Hydrated volcanic glass (SiO2 with inclusions)
igneous
Snowflake Obsidian
Volcanic glass containing Spherulitic Cristobalite (SiO2)
igneous
Garnet
Almandine (Fe3Al2(SiO4)3)
mineral
Diamond (Round Brilliant Cut)
Diamond (Pure Carbon, C)
mineral
Asphalt (Bituminous Concrete)
Bituminous mix / Anthropogenic conglomerate
man-made composite (lithified equivalent of sedimentary)
Native Copper (Penny specimen)
Native Copper (Cu)
mineral
Quartz (Milky/Smoky variety)
Silicon Dioxide (SiO2)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
sedimentary
Diamond
Diamond (C)
mineral
Chert (Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Ferruginous Quartz
Iron-stained Quartz (Silicon Dioxide + Fe2O3 / FeO(OH))
mineral
Blue Calcite
Calcium Carbonate (CaCO3)
mineral
Quartz (specifically a water-worn river pebble)
Silicon Dioxide (SiO2)
Mineral
Agate (specifically a Thunderegg/Agate Nodule)
Cryptocrystalline Quartz (SiO2)
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Glass / Silicon Dioxide (Man-made)
SiO2 (Amorphous Silicon Dioxide)
Amorphous Solid
Rainbow Obsidian
Volcanic glass (SiO2 - approximately 70% or more silicon dioxide)
Igneous
White Topaz
Topaz - Al2SiO4(F,OH)2
mineral
Diamond (or Cubic Zirconia)
Carbon (C) / Cubic Zirconium Dioxide (ZrO2)
mineral
Almandine Garnet
Almandine, Fe3Al2(SiO4)3
mineral
Magnetite Sand (Black Sand)
Magnetite (Fe3O4)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
Mineral
Apache Tear
Hydrated Obsidians (Volcanic Glass)
igneous
Tektite (Indochinite)
Tektite (impactite), primarily high-silica glass (SiO2)
igneous
Quartzite
Quartzite (SiO2)
metamorphic
Milky Quartz
Crystalline Silicon Dioxide (SiO2)
mineral
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Fluorite (likely Fluorite on Quartz/Matrix)
Calcium Fluoride (CaF2)
mineral
Asphalt (Bituminous Concrete)
Bituminous Concrete / Pavement
man-made (synthetic rock)
Banded Chert
Chert (a microcrystalline variety of quartz, SiO2 with minor impurities)
Sedimentary