Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Category
Browse organic mineraloid specimens identified by the Rock Identifier community.
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Black Obsidian
Volcanic Glass (SiO2)
Snowflake Obsidian
Volcanic glass containing Spherulitic Cristobalite (SiO2)
Mahogany Obsidian
Volcanic Glass with Hematite inclusions (SiO2 + Fe2O3)
Obsidian
Volcanic Glass (70-75% SiO2)
Opal
Hydrated Silica (SiO2·nH2O)
Gold Sheen Obsidian
Obsidian (volcanic glass with SiO2 + gas inclusions)
White Precious Opal
Hydrated Silica (SiO2·nH2O)
Limonite (Hydrated Iron Oxide / Bog Iron)
FeO(OH)·nH2O
Obsidian
Volcanic Glass (SiO2)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)
Obsidian
Volcanic Glass (SiO2)
Opalite
Man-made opalescent glass
Gold Sheen Obsidian
Volcanic Glass (SiO2 + impurities)
Obsidian
Amorphous volcanic glass (SiO2)
Obsidian
Volcanic Glass (SiO2)
Obsidian
Obsidian (Volcanic Glass)
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (70-75% SiO2)
Limonite (Iron Ore)
Limonite (Hydrous ferric oxides), generic formula FeO(OH)·nH2O
Black Opal Ring (Carved Opal)
Hydrated Silicon Dioxide (SiO2·nH2O)
Opal (Precious Opal)
Hydrated Silica (SiO2·nH2O)
Mahogany Obsidian
Volcanic Glass with Hematite inclusions
Black Obsidian
Volcanic Glass (SiO2 + MgO / Fe3O4)
Black Obsidian
Volcanic Glass (SiO2)
Snowflake Obsidian
Volcanic glass (SiO2) with Cristobalite (SiO2) inclusions
Snowflake Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with Cristobalite inclusions)
Obsidian
Obsidian (volcanic glass; primarily SiO2)
Mahogany Obsidian
Obsidian (Volcanic Glass with Hematite/Magnetite inclusions), SiO2
Obsidian
Volcanic Glass (70-75% SiO2 with MgO and Fe3O4)
Limonite (Iron-rich Siltstone / Sandstone base)
Hydrous ferric oxide mixture (FeO(OH)·nH2O)
Obsidian
Volcanic glass (high silica volcanic rock)
Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2
Limonite (Iron Ore Congcretion)
Limonite (a mixture of hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)
Tumbled mahogany obsidian
Volcanic glass; primarily SiO₂ with iron-oxide-rich brown inclusions
Opalite
Synthetic Glass (Silica-based)
Black Obsidian
Amorphous volcanic glass (SiO2)
Obsidian (specifically Mahogany Obsidian)
Volcanic glass (high silica content, SiO2)
Obsidian with Mahogany Phasing
Volcanic Glass (SiO2 + Fe2O3)
Obsidian
Obsidian (Volcanic Glass; SiO2 content > 70%)