Rock Identifier

Category

Organic Crystal (Mineraloid)

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

Jet (Lignite (Anthracite-grade compact coal)) — sedimentary

Jet

Lignite (Anthracite-grade compact coal)

Obsidian (Amorphous volcanic glass (primarily SiO2)) — igneous

Obsidian

Amorphous volcanic glass (primarily SiO2)

Snowflake Obsidian (Volcanic Glass with Cristobalite inclusions (70–75% SiO2)) — Igneous

Snowflake Obsidian

Volcanic Glass with Cristobalite inclusions (70–75% SiO2)

Limonite (Iron Stone/Ocher) (Limonite (FeO(OH)·nH2O)) — mineral

Limonite (Iron Stone/Ocher)

Limonite (FeO(OH)·nH2O)

Limonite (Yellow Ochre) (Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)) — mineral

Limonite (Yellow Ochre)

Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)

Obsidian (Obsidian (Volcanic Glass)) — igneous

Obsidian

Obsidian (Volcanic Glass)

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

Obsidian

Volcanic glass (mainly SiO2 with inclusions)

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

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

Mahogany Obsidian

Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)

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

Obsidian

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

Obsidian (Obsidian (Volcanic Glass)) — igneous

Obsidian

Obsidian (Volcanic Glass)

Obsidian (Obsidian (Volcanic Glass, SiO2 + impurities)) — igneous

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

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

Black Obsidian

Volcanic Glass (SiO2 + impurities like Fe3O4)

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

Opal

Hydrated Silica (SiO2·nH2O)

Obsidian (Volcanic Glass (70-75% SiO2)) — igneous

Obsidian

Volcanic Glass (70-75% SiO2)

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

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)

Limonite (Hydrated Iron Oxide / Bog Iron) (FeO(OH)·nH2O) — Mineral (Sedimentary context)

Limonite (Hydrated Iron Oxide / Bog Iron)

FeO(OH)·nH2O

Mineral (Sedimentary context)

Baltic Amber (Butterscotch or Egg Yolk Variety) (Succinite (C10H16O)) — Organic Gemstone (Mineraloid)

Baltic Amber (Butterscotch or Egg Yolk Variety)

Succinite (C10H16O)

Organic Gemstone (Mineraloid)

Mahogany Obsidian (Volcanic glass (SiO2 + Fe2O3)) — igneous

Mahogany Obsidian

Volcanic glass (SiO2 + Fe2O3)

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

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Black Obsidian (Volcanic Glass (predominantly SiO2, Silicon Dioxide)) — igneous

Black Obsidian

Volcanic Glass (predominantly SiO2, Silicon Dioxide)

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)

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

Green Opal

Hydrated Silica (SiO2·nH2O)

Obsidian (Obsidian (Extrusive Volcanic Glass)) — igneous

Obsidian

Obsidian (Extrusive Volcanic Glass)

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

Limonite (Iron Ore)

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

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

Precious Opal

Hydrated Silica (SiO2·nH2O)

Amber (Succinite) — Mineraloid

Amber

Succinite

Fulgurite (Luechatelierite (SiO2 glass)) — mineraloid

Fulgurite

Luechatelierite (SiO2 glass)

Black Obsidian (Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)) — igneous

Black Obsidian

Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)

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

Common Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Limonite (Ironstone) (Limonite (Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O)) — mineral

Limonite (Ironstone)

Limonite (Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O)

Common Opal in Host Rock (Hydrated Silica (SiO2·nH2O)) — mineraloid

Common Opal in Host Rock

Hydrated Silica (SiO2·nH2O)

Glass (Amorphous Silicon Dioxide (SiO2)) — mineraloid

Glass

Amorphous Silicon Dioxide (SiO2)

Black Opal (Hydrated Silica (SiO2·nH2O)) — Mineraloid

Black Opal

Hydrated Silica (SiO2·nH2O)

Limonite (Yellow Ochre) (Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)) — mineral

Limonite (Yellow Ochre)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Limonite (Yellow Ochre) (Limonite (Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O)) — mineral

Limonite (Yellow Ochre)

Limonite (Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O)

Cullet Glass (Man-made Glass Slag) (Amorphous Silica (SiO2) with chemical additives) — Mineraloid

Cullet Glass (Man-made Glass Slag)

Amorphous Silica (SiO2) with chemical additives

Tektite (Indochinite) (Tektite (High-silica impact glass)) — mineraloid

Tektite (Indochinite)

Tektite (High-silica impact glass)

Cullet (Slag Glass) (Amorphous Silica (Industrial byproduct)) — mineraloid

Cullet (Slag Glass)

Amorphous Silica (Industrial byproduct)