Rock Identifier

Category

Organic Crystal (Mineraloid)

Browse organic crystal (mineraloid) specimens identified by the Rock Identifier community.

Obsidian (Volcanic Glass (Amorphous SiO2)) — igneous

Obsidian

Volcanic Glass (Amorphous SiO2)

Obsidian (Obsidian (Volcanic Glass)) — igneous

Obsidian

Obsidian (Volcanic Glass)

Limonite/Goethite on Shale (Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock) — sedimentary

Limonite/Goethite on Shale

Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock

Obsidian (Volcanic glass) — igneous

Obsidian

Volcanic glass

Polished black stone, likely black obsidian (Obsidian (volcanic glass), primarily rhyolitic silica glass) — igneous

Polished black stone, likely black obsidian

Obsidian (volcanic glass), primarily rhyolitic silica glass

Mahogany Obsidian (Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)) — igneous

Mahogany Obsidian

Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)

Obsidian (Volcanic glass (mainly SiO2 with inclusions)) — igneous

Obsidian

Volcanic glass (mainly SiO2 with inclusions)

Opal (Hydrated Silica (SiO2·nH2O)) — mineraloid

Opal

Hydrated Silica (SiO2·nH2O)

Tumbled black stone, likely black obsidian (Obsidian — volcanic glass, primarily SiO₂) — igneous

Tumbled black stone, likely black obsidian

Obsidian — volcanic glass, primarily SiO₂

Precious Opal (Hydrated Silica (SiO2·nH2O)) — mineral

Precious Opal

Hydrated Silica (SiO2·nH2O)

Snowflake Obsidian (Volcanic Glass with Cristobalite Inclusions) — igneous

Snowflake Obsidian

Volcanic Glass with Cristobalite Inclusions

Opal (Hydrated Amorphous Silica (SiO2·nH2O)) — Mineral

Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Opal (Hydrated silica (SiO2 · nH2O)) — mineraloid

Opal

Hydrated silica (SiO2 · nH2O)

Obsidian (Obsidian (volcanic glass), primarily SiO2 (silicon dioxide)) — igneous

Obsidian

Obsidian (volcanic glass), primarily SiO2 (silicon dioxide)

Likely obsidian (rough fragment) (Volcanic glass, predominantly silica-rich rhyolitic composition (SiO₂-rich, noncrystalline)) — igneous

Likely obsidian (rough fragment)

Volcanic glass, predominantly silica-rich rhyolitic composition (SiO₂-rich, noncrystalline)

Green Opal (Hydrated amorphous silica (SiO2·nH2O)) — mineraloid

Green Opal

Hydrated amorphous silica (SiO2·nH2O)

Limonite (Iron Ore) (Limonite (FeO(OH)·nH2O)) — mineral

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Black Obsidian (Volcanic Glass (SiO2 + impurities like Fe3O4)) — igneous

Black Obsidian

Volcanic Glass (SiO2 + impurities like Fe3O4)

Snowflake Obsidian (Volcanic Glass (spherulitic Obsidian) - SiO2 (with Cristobalite inclusions)) — igneous

Snowflake Obsidian

Volcanic Glass (spherulitic Obsidian) - SiO2 (with Cristobalite inclusions)

Obsidian (black volcanic glass) (Obsidian; predominantly rhyolitic volcanic glass, mainly SiO₂ with minor feldspar, quartz, and iron oxides) — igneous

Obsidian (black volcanic glass)

Obsidian; predominantly rhyolitic volcanic glass, mainly SiO₂ with minor feldspar, quartz, and iron oxides

Obsidian (Volcanic glass (SiO2 - Silicon Dioxide with impurities)) — igneous

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide with impurities)

Mahogany Obsidian (Obsidian (volcanic glass with hematite/magnetite inclusions)) — igneous

Mahogany Obsidian

Obsidian (volcanic glass with hematite/magnetite inclusions)

Precious Opal (Hydrated Silica (SiO2·nH2O)) — mineral

Precious Opal

Hydrated Silica (SiO2·nH2O)

Limonite (Iron Ore) (Limonite (Hydrous ferric oxides), generic formula FeO(OH)·nH2O) — mineral

Limonite (Iron Ore)

Limonite (Hydrous ferric oxides), generic formula FeO(OH)·nH2O

Bumblebee Jasper (Anhydrite-Aragonite mixture with Orpiment and Realgar) — mineraloid

Bumblebee Jasper

Anhydrite-Aragonite mixture with Orpiment and Realgar

Conch Pearl (Calcareous concretion (CaCO3)) — mineraloid

Conch Pearl

Calcareous concretion (CaCO3)

Libyan Desert Glass (Natural Silica Glass (SiO2 with minor iron and titanium)) — mineraloid

Libyan Desert Glass

Natural Silica Glass (SiO2 with minor iron and titanium)

Amber (Succinite (C10H16O)) — mineraloid

Amber

Succinite (C10H16O)

Fulgurite (Liesegang (Fulgurite)) — Mineraloid

Fulgurite

Liesegang (Fulgurite)

Limonite (Iron Ore) (Limonite (Hydrated iron oxide - FeO(OH)·nH2O)) — mineral

Limonite (Iron Ore)

Limonite (Hydrated iron oxide - FeO(OH)·nH2O)

Obsidian (Volcanic glass) — igneous

Obsidian

Volcanic glass

Sea Glass (Frosted Quartz/Glass) (Amorphous Silicon Dioxide (SiO2)) — Mineraloid

Sea Glass (Frosted Quartz/Glass)

Amorphous Silicon Dioxide (SiO2)

White Opal (Hydrated Amorphous Silica (SiO2·nH2O)) — Mineraloid

White Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Black Opal (Hydrated silica (SiO2·nH2O)) — mineraloid

Black Opal

Hydrated silica (SiO2·nH2O)

Dragon's Breath (Mexican Opal Glass) (Artisan Foil Glass (SiO2 based)) — mineraloid

Dragon's Breath (Mexican Opal Glass)

Artisan Foil Glass (SiO2 based)

Sea Glass (often mistaken for Gemstones) (Amorphous Silica (SiO2) with trace additives) — mineraloid

Sea Glass (often mistaken for Gemstones)

Amorphous Silica (SiO2) with trace additives

Opal (Hydrated Silica (SiO2·nH2O)) — mineral

Opal

Hydrated Silica (SiO2·nH2O)

Common Opal (SiO2·nH2O (Hydrated Silicon Dioxide)) — mineraloid

Common Opal

SiO2·nH2O (Hydrated Silicon Dioxide)

Common Opal (Hydrated Amorphous Silica (SiO2·nH2O)) — mineraloid

Common Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Pearl (Aragonite / Calcium Carbonate (CaCO3)) — mineraloid

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Opalite (Man-made synthetic glass with opalescent effects (SiO2 + metal oxides)) — mineraloid

Opalite

Man-made synthetic glass with opalescent effects (SiO2 + metal oxides)

Cullet Glass (Slag Glass) (Amorphous Silicon Dioxide (Industrial Byproduct)) — mineraloid

Cullet Glass (Slag Glass)

Amorphous Silicon Dioxide (Industrial Byproduct)