Fire Opal (in Matrix)
Hydrated Silica (SiO2·nH2O)
Category
Browse mineraloid (anthropogenic) specimens identified by the Rock Identifier community.
Fire Opal (in Matrix)
Hydrated Silica (SiO2·nH2O)
Obsidian (likely black volcanic glass)
Obsidian; predominantly silica-rich rhyolitic volcanic glass (approximately 70– on 80% SiO₂)
Polished black obsidian
Volcanic glass, predominantly rhyolitic silica (SiO₂)
Likely obsidian fragment
Volcanic glass, predominantly silica-rich rhyolitic composition (SiO₂-rich)
Obsidian (likely Apache tear or flaked obsidian)
Volcanic glass; primarily rhyolitic silica glass (SiO₂-rich, non-crystalline)
Mahogany Obsidian
Obsidian (Volcanic Glass with Hematite inclusions)
Gold Sheen Obsidian
Volcanic Glass (SiO2 + impurities)
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite/Magnetite inclusions)
Polished mahogany obsidian (likely)
Volcanic glass; primarily silica-rich rhyolitic glass (SiO₂), with iron oxides
Polished black obsidian pyramid/block
Obsidian — natural volcanic glass, chiefly rhyolitic silica (approximately 70–75% SiO₂)
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (primarily SiO2)
Black Obsidian
Obsidian (Volcanic Glass)
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (70–75% SiO2)
Limonitic Iron Ore / Goethite
Hydrated Iron(III) oxide-hydroxide (primarily FeO(OH)·nH2O)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Obsidian
Obsidian (Volcanic Glass, SiO2)
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
Mahogany Obsidian
Volcanic Glass (predominantly SiO2 with inclusions of Hematite or Magnetite)
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite or Magnetite inclusions)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
Obsidian
Obsidian
Polished black obsidian
Volcanic glass; primarily silica-rich rhyolitic glass (approximately 70–80% SiO₂)
Polished black obsidian
Volcanic glass; primarily silica-rich rhyolitic composition (approximately 70–80% SiO₂)
Black obsidian
Volcanic glass; predominantly rhyolitic silica-rich melt (approximately 70–80% SiO₂), lacking crystalline structure
Obsidian (likely snowflake-free black variety)
Volcanic glass; primarily SiO₂-rich rhyolitic composition
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
Black Obsidian
Obsidian (Volcanic Glass, ~70% SiO2)
Obsidian
Volcanic Glass (SiO2)
Snowflake Obsidian (Flower Jasper variant)
Vitreous volcanic silicate with cristobalite inclusions
Mahogany Obsidian
Volcanic Glass (Silicate: SiO2 + Fe2O3)
Obsidian
Volcanic Glass (SiO2 rich)
Limonite (with Pyrite)
Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O
Limonite (Ironstone Concretion)
Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)
Obsidian Arrowhead
Volcanic Glass (Primary composition: SiO2)
Polished mahogany obsidian
Volcanic glass; primarily silica-rich rhyolitic composition (approximately 70–75% SiO₂)
Bumblebee Jasper
Calcite with Arsenic and Sulfur inclusions
Obsidian
Obsidian (Volcanic Glass)
Obsidian (Gold Sheen)
Obsidian (SiO2 + impurities)
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
Snowflake Obsidian
Volcanic Glass (SiO2) with Cristobalite inclusions