Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
igneous
Category
Mineraloid
Browse mineraloid specimens identified by the Rock Identifier community.
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Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
igneous
Obsidian
Obsidian (Volcanic Glass), primarily SiO2
igneous
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
mineral
Limonite (Iron Ore Congcretion)
Limonite (a mixture of hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)
mineral
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
igneous
Black Obsidian
Obsidian (Volcanic Glass, ~70% SiO2)
igneous
Obsidian
Volcanic Glass (SiO2)
igneous
Snowflake Obsidian (Flower Jasper variant)
Vitreous volcanic silicate with cristobalite inclusions
igneous
Mahogany Obsidian
Volcanic Glass (Silicate: SiO2 + Fe2O3)
igneous
Obsidian
Volcanic Glass (SiO2 rich)
Igneous
Limonite (Ironstone Concretion)
Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)
sedimentary
Limonite (with Pyrite)
Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O
mineral
Pearl (Biogenic Mineraloid)
Calcium carbonate (CaCO3) primarily as Aragonite
mineral
Fire Opal (in Matrix)
Hydrated Silica (SiO2·nH2O)
mineral
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (primarily SiO2)
igneous
Black Obsidian
Obsidian (Volcanic Glass)
igneous
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (70–75% SiO2)
igneous
Limonitic Iron Ore / Goethite
Hydrated Iron(III) oxide-hydroxide (primarily FeO(OH)·nH2O)
sedimentary
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Obsidian
Obsidian (Volcanic Glass, SiO2)
igneous
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
mineral
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with inclusions of Hematite or Magnetite)
igneous
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
igneous
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
mineral
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
igneous
Mahogany Obsidian
Volcanic glass (Silicon Dioxide with Hematite/Magnetite inclusions)
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (SiO2 + impurities)
igneous
Limonite Concretion
Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)
sedimentary
Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Pearl (Biogenic Mineral)
Calcium Carbonate (primarily Aragonite) with Conchiolin; CaCO3
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Obsidian (Gold Sheen)
Obsidian (SiO2 + impurities)
igneous
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
igneous
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
igneous
Snowflake Obsidian
Volcanic Glass (SiO2) with Cristobalite inclusions
igneous
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Pearl (Biogenic Mineraloid)
Calcium carbonate (Aragonite) and Conchiolin, CaCO3
mineral
Yellow Ocher (Limonite)
Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O
mineral
Limonite (Iron Ore/Sandstone mixture)
Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix
mineral
Precious Coral (Red Coral)
Corallium rubrum (Calcium Carbonate, CaCO3)
mineral