Rock Identifier

Category

Organic Crystal (Mineraloid)

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

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

Limonite (Iron Ore)

Hydrous ferric oxides (FeO(OH)·nH2O)

Tektite (likely Australite) (Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)) — Mineral (specifically a mineraloid)

Tektite (likely Australite)

Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)

Mineral (specifically a mineraloid)

Polished mahogany obsidian (Volcanic glass; predominantly rhyolitic silica glass (SiO₂-rich)) — igneous

Polished mahogany obsidian

Volcanic glass; predominantly rhyolitic silica glass (SiO₂-rich)

Limonite Concretion (Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)) — sedimentary

Limonite Concretion

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

Polished black obsidian (Volcanic glass; predominantly rhyolitic silica glass (approximately 70–80% SiO₂)) — igneous

Polished black obsidian

Volcanic glass; predominantly rhyolitic silica glass (approximately 70–80% SiO₂)

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

Black Obsidian

Obsidian (Volcanic Glass, SiO2+)

Snowflake Obsidian (Spherulitic Volcanic Glass (SiO2 + impurities)) — igneous

Snowflake Obsidian

Spherulitic Volcanic Glass (SiO2 + impurities)

Obsidian (Volcanic Glass (Silica / SiO2)) — igneous

Obsidian

Volcanic Glass (Silica / SiO2)

Opalite (Man-made opalescent glass) — gemstone

Opalite

Man-made opalescent glass

Obsidian (Volcanic Glass (predominantly SiO2, approximately 70% or more)) — igneous

Obsidian

Volcanic Glass (predominantly SiO2, approximately 70% or more)

Mahogany Obsidian (Volcanic Glass (predominantly SiO2 with Fe2O3 inclusions)) — igneous

Mahogany Obsidian

Volcanic Glass (predominantly SiO2 with Fe2O3 inclusions)

Limonite (Iron Ore/Sandstone mixture) (Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix) — mineral

Limonite (Iron Ore/Sandstone mixture)

Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix

Tumbled black stone, likely obsidian (Obsidian — volcanic glass, chiefly silica-rich rhyolitic composition) — igneous

Tumbled black stone, likely obsidian

Obsidian — volcanic glass, chiefly silica-rich rhyolitic composition

Mahogany Obsidian (Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)) — igneous

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)

Snowflake Obsidian (Volcanic glass containing Spherulites (SiO2)) — igneous

Snowflake Obsidian

Volcanic glass containing Spherulites (SiO2)

Yellow Ocher (Limonite) (Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O) — mineral

Yellow Ocher (Limonite)

Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O

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

Obsidian

Obsidian (volcanic glass; primarily SiO2)

Limonite (Iron Ore) (Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)) — Mineral

Limonite (Iron Ore)

Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)

Obsidian (Volcanic glass (Amorphous silicon dioxide)) — igneous

Obsidian

Volcanic glass (Amorphous silicon dioxide)

Amber (and Citrine Quartz) (Succinite (Amber) and Silicon Dioxide (SiO2)) — Organic Mineraloid and Mineral

Amber (and Citrine Quartz)

Succinite (Amber) and Silicon Dioxide (SiO2)

Organic Mineraloid and Mineral

Baltic Amber (Butterscotch variety) (Succinite) — Organic Gemstone/Mineraloid

Baltic Amber (Butterscotch variety)

Succinite

Organic Gemstone/Mineraloid

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

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Obsidian (Obsidian (Volcanic Glass)) — igneous

Obsidian

Obsidian (Volcanic Glass)

Amber (Resinite / Fossilized Tree Resin) — mineral

Amber

Resinite / Fossilized Tree Resin

Obsidian (Black Obsidian) (Obsidian (Volcanic Glass)) — igneous

Obsidian (Black Obsidian)

Obsidian (Volcanic Glass)

Limonite (Ironstone) Concretion (FeO(OH)·nH2O (Hydrous ferric oxide)) — sedimentary

Limonite (Ironstone) Concretion

FeO(OH)·nH2O (Hydrous ferric oxide)

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

Obsidian

Volcanic Glass (SiO2 + impurities)

Snowflake Obsidian (Volcanic Glass with Spherulite inclusions (Chemical composition: 70–75% SiO2 + MgO, Fe3O4)) — igneous

Snowflake Obsidian

Volcanic Glass with Spherulite inclusions (Chemical composition: 70–75% SiO2 + MgO, Fe3O4)

Opalite (Man-made Glass (Synthetic Opalized Glass)) — gemstone

Opalite

Man-made Glass (Synthetic Opalized Glass)

Naga Silver-Inlaid Ebony and Bone/Horn Beads (Diospyros (Ebony) or Keratin (Horn) with Silver/White-Metal Inlay) — Organic (Anthropological Artifact)

Naga Silver-Inlaid Ebony and Bone/Horn Beads

Diospyros (Ebony) or Keratin (Horn) with Silver/White-Metal Inlay

Organic (Anthropological Artifact)

Mahogany Obsidian (Volcanic glass containing Magnetite/Hematite) — igneous

Mahogany Obsidian

Volcanic glass containing Magnetite/Hematite

Opalite (Synthetic Glass (Hydrated Crystalline Silicon Dioxide simulation)) — mineral

Opalite

Synthetic Glass (Hydrated Crystalline Silicon Dioxide simulation)

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

Black Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Obsidian (Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)) — igneous

Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Mahogany Obsidian (Volcanic Glass (SiO2 with Fe/Mg oxides)) — igneous

Mahogany Obsidian

Volcanic Glass (SiO2 with Fe/Mg oxides)

Mahogany Obsidian Arrowhead (Volcanic Glass with Hematite/Magnetite inclusions (Amorphous Silicon Dioxide)) — igneous

Mahogany Obsidian Arrowhead

Volcanic Glass with Hematite/Magnetite inclusions (Amorphous Silicon Dioxide)

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

Obsidian

Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)

Limonite with Quartz (Gossan) (Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)) — Mineral

Limonite with Quartz (Gossan)

Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)

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

Common Opal (Potch)

Hydrated Silica (SiO2·nH2O)

Limonite and Goethite (Ironstone) (Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)) — sedimentary

Limonite and Goethite (Ironstone)

Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)

Ambergris (Ambrein (C30H52O)) — mineraloid / organic geological substance

Ambergris

Ambrein (C30H52O)

mineraloid / organic geological substance

Polished black stone egg, probably black obsidian (Obsidian, a natural volcanic glass; composition primarily silica-rich glass (approximately SiO₂), with variable iron and other trace elements) — gemstone

Polished black stone egg, probably black obsidian

Obsidian, a natural volcanic glass; composition primarily silica-rich glass (approximately SiO₂), with variable iron and other trace elements