Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Category
Browse mineraloid (man made origin) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Opal (in Jewelry Setting)
Hydrated Silicon Dioxide (SiO2·nH2O)
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Manganese Dendrite on Siltstone
Manganese Oxide (pyrolusite or psilomelane) Dendrites
Gold Sheen Obsidian
Volcanic Glass (SiO2 + impurities)
Kidney Stone
Nephrolithiasis (Calcium Oxalate, Hydroxyapatite, or Uric Acid)
Sapphire
Corundum (Al2O3)
Diamond (in a gold ring)
Diamond (pure carbon, C)
Granodiorite
Granodiorite
Black Pearl (Tahitian Pearl)
Aragonite / Calcite (CaCO3) with Conchiolin
Possible basalt or other dark volcanic rock
Undetermined fine-grained mafic volcanic rock; basalt is a possibility
Obsidian arrowhead
Volcanic glass; predominantly SiO₂, with minor feldspar, pyroxene, and iron oxides
Mahogany Obsidian
Volcanic Glass with Hematite (SiO2 + Fe2O3)
Black Obsidian
Volcanic Glass (SiO2 + impurities like Fe3O4)
Opal
Hydrated silica (SiO2 "NH2O)
Snowflake Obsidian
Spherulitic Obsidian (Volcanic Glass with Cristobalite inclusions)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Snowflake Obsidian
Hydrated Volcanic Glass (primarily SiO2) with Cristobalite inclusions
Obsidian
Volcanic Glass (SiO2)
Amber
Amber (C10H16O)
Opal
Hydrated amorphous silica (SiO2·nH2O)
Chert (Flint) Artifact
Silicon Dioxide (SiO2)
Emerald
Beryl (Be3Al2(SiO3)6)
Tumbled aqua glassy mineral specimen, likely chrysocolla or turquoise imitation
Uncertain from image; possible chrysocolla (hydrated copper aluminosilicate, variable composition) or dyed/man-made glass
Purple Slate
Foliated slate (Pelitic origin)
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)
Obsidian
Volcanic Glass (SiO2)
Blue tumbled glass-like specimen; likely blue slag glass
Likely man-made glass (silicate glass), not a natural mineral; exact material cannot be confirmed from the image
Chondrite Meteorite
Ordinary Chondrite (S-type asteroid origin)
Blue-gray mineral specimen (possibly sodalite)
Undetermined; appearance may be consistent with sodalite (Na₈Al₆Si₆O₂₄Cl₂), but the image is insufficient for reliable identification
Green cabochon, likely dyed or imitation material
Undetermined; the image is insufficient to identify a mineral species
Note: Item is not a geological specimen
Homo sapiens (Dermal Appendage: Pilus)
Diamond
Carbon (C)
Precious Opal
SiO2·nH2O (Hydrated Silicon Dioxide)
Black obsidian (likely)
Volcanic glass; primarily silica-rich, noncrystalline SiO₂ composition
Polished black stone, likely black obsidian
Obsidian (volcanic glass), primarily rhyolitic silica glass
Obsidian
Obsidian (volcanic glass), primarily SiO2 (silicon dioxide)
Obsidian
Volcanic glass (mainly SiO2 with inclusions)
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
Obsidian
Obsidian (Volcanic Glass)
Limonite (Iron Stone/Ocher)
Limonite (FeO(OH)·nH2O)