Chalcedony (or a variety of Chalcedony, likely Agate or Jasper)
Chalcedony (SiO₂)
Category
Browse mineral (or mineraloid if microcrystalline) specimens identified by the Rock Identifier community.
Chalcedony (or a variety of Chalcedony, likely Agate or Jasper)
Chalcedony (SiO₂)
Native Sulfur
Sulfur (S8)
Limonite (Ironstone)
Limonite (mixture of hydrated iron oxides, primarily Goethite α-FeO(OH))
Limonite (Iron Stone/Ocher)
Limonite (FeO(OH)·nH2O)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)
Limonite (Iron Stone/Goethite)
Limonite (mixture of hydrated iron oxides, primarily Goethite: α-FeO(OH))
Limonite (Ironstone Concretion)
Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)
Limonite (Iron Ore/Sandstone mixture)
Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix
Limonite Concretion
Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)
Pearl (Biogenic Mineral)
Calcium Carbonate (primarily Aragonite) with Conchiolin; CaCO3
Limonite with Quartz (Gossan)
Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)
Pearl
Calcium Carbonate (Aragonite) with Conchiolin; formula: CaCO3
Black Obsidian
Volcanic Glass (SiO2 + impurities)
Black Pearl (Tahitian Pearl)
Aragonite / Calcite (CaCO3) with Conchiolin
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
Amber
Succinite (Organic Mineraloid)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Gold Sheen Obsidian
Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)
Pearl
Aragonite / Calcium Carbonate (CaCO3)
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Amber in Matrix
Succinite (Carbon-based organic polymer)
Obsidian
Obsidian (Amorphous volcanic glass, predominantly SiO2)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Obsidian
Volcanic Glass (SiO2 rich)
Limonite (Iron Ore)
Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)
Limonite (Iron Ore)
Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Jet
Lignite (Anthracite-grade compact coal)
Opal
Hydrated Silica (SiO2·nH2O)
Pearl
Aragonite / Calcium Carbonate (CaCO3)
Conch Pearl
Calcareous concretion (CaCO3)
Pearl
Aragonite and Conchiolin (CaCO3 + organic protein)
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
Obsidian
Amorphous volcanic glass (primarily SiO2)
Obsidian
Obsidian (Volcanic Glass)
Limonite/Goethite on Shale
Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock
Black Obsidian
Volcanic Glass (SiO2 + impurities like Fe3O4)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Snowflake Obsidian
Hydrated Volcanic Glass (primarily SiO2) with Cristobalite inclusions