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)
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/Goethite Concretion
Hydrated Iron(III) Oxide-hydroxide (FeO(OH)·nH2O)
Limonite (Iron Stone/Goethite)
Limonite (mixture of hydrated iron oxides, primarily Goethite: α-FeO(OH))
Native Sulfur
Sulfur (S8)
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
Quartzite with Iron Inclusions
Quartzite (pre d om i n a n t l y SiO2) with H e m a t i t e / G o e t h i t e
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
Obsidian
Volcanic glass (SiO2 + impurities)
Limonite or Ironstone Nodule
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
Black Obsidian
Volcanic Glass (predominantly SiO2)
Amber
Succinite (Organic Mineraloid)
Black Obsidian
Volcanic Glass (Amorphous SiO2 with trace impurities)
Pearl (Biogenic Mineraloid)
Calcium carbonate (CaCO3) primarily as Aragonite
Black Pearl (Tahitian Pearl)
Aragonite / Calcite (CaCO3) with Conchiolin
Black Obsidian
Volcanic glass
Obsidian
Volcanic Glass
Obsidian
Volcanic Glass (Amorphous silicon dioxide with impurities)
Obsidian
Volcanic Glass (SiO2 + impurities)
Black Obsidian
Volcanic Glass (SiO2 + impurities)
Gold Sheen Obsidian
Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)
Mahogany Obsidian
Volcanic glass (high silica) with inclusions of Magnetite or Hematite
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
Pearl
Aragonite / Calcium Carbonate (CaCO3)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Obsidian
Volcanic Glass (Amorphous SiO2)
Polished mahogany obsidian (probable)
Volcanic glass; chiefly rhyolitic silica-rich glass (SiO₂), compositionally near rhyolite
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Obsidian
Volcanic Glass (SiO2 rich)
Limonite (Iron Ore)
Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
Obsidian
Volcanic Glass (70% or more SiO2)
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