Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Category
Browse mineral (or mineraloid if microcrystalline) specimens identified by the Rock Identifier community.
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Black Obsidian
Volcanic Glass (SiO2)
Mahogany Obsidian
Volcanic Glass with Hematite inclusions (SiO2 + Fe2O3)
Obsidian
Volcanic Glass (70-75% SiO2)
Limonite (Hydrated Iron Oxide / Bog Iron)
FeO(OH)·nH2O
Obsidian
Volcanic Glass (SiO2)
Pearl (nacre)
Calcium Carbonate (mostly CaCO3 as Aragonite) and Conchiolin
Amber
Succinite (organic mineraloid); Chemical formula: C10H16O
Glass
Amorphous Silicon Dioxide (SiO2)
Amber
Succinite
Limonite (Iron-rich Siltstone / Sandstone base)
Hydrous ferric oxide mixture (FeO(OH)·nH2O)
Obsidian
Amorphous volcanic glass (SiO2)
Obsidian
Volcanic Glass (SiO2)
Obsidian
Obsidian (Volcanic Glass)
Common Opal (Green Opal / Pistachio Opal)
Hydrated silica (SiO2·nH2O)
Amber
Succinite (C10H16O)
Mahogany Obsidian
Volcanic Glass with Hematite (SiO2 + Fe2O3)
Green Opal or Yellow Opal
Hydrated Silica (SiO2·nH2O)
Snowflake Obsidian
Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)
Limonite (Iron Ore Congcretion)
Limonite (a mixture of hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
Mahogany Obsidian
Volcanic Glass with Hematite inclusions
Black Obsidian
Volcanic Glass (SiO2 + MgO / Fe3O4)
Black Obsidian
Volcanic Glass (SiO2)
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)
Obsidian
Volcanic glass (high silica volcanic rock)
Black Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Polished black obsidian pyramid/block
Obsidian — natural volcanic glass, chiefly rhyolitic silica (approximately 70–75% SiO₂)
Tumbled mahogany obsidian
Volcanic glass; primarily SiO₂ with iron-oxide-rich brown inclusions
Black Obsidian
Amorphous volcanic glass (SiO2)
Obsidian (specifically Mahogany Obsidian)
Volcanic glass (high silica content, SiO2)
Obsidian
Obsidian (Volcanic Glass; SiO2 content > 70%)
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Obsidian
Volcanic glass
Obsidian
Volcanic glass (mainly SiO2 with inclusions)
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions (70–75% SiO2)
Amber (Black)
Amber (succinite, retinite, etc., specifically, heavily included/dark varieties)
Limonitic Iron Ore / Goethite
Hydrated Iron(III) oxide-hydroxide (primarily FeO(OH)·nH2O)