Precious Opal
Hydrated Silica (SiO2·nH2O)
Category
Browse mineraloid specimens identified by the Rock Identifier community.
Precious Opal
Hydrated Silica (SiO2·nH2O)
Limonite/Ironstone
Limonite (FeO(OH)·nH2O)
Opal
Hydrated Silica (SiO2·nH2O)
Limonite (Ironstone)
Limonite (mixture of hydrated iron(III) oxide-hydroxides)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Opal (in Jewelry Setting)
Hydrated Silicon Dioxide (SiO2·nH2O)
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Mahogany Obsidian
Volcanic Glass with Hematite (SiO2 + Fe2O3)
Black Obsidian
Volcanic Glass (SiO2 + impurities like Fe3O4)
Opal
Hydrated silica (SiO2 "NH2O)
Snowflake Obsidian
Spherulitic Obsidian (Volcanic Glass with Cristobalite inclusions)
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurities)
Snowflake Obsidian
Hydrated Volcanic Glass (primarily SiO2) with Cristobalite inclusions
Obsidian
Volcanic Glass (SiO2)
Amber
Amber (C10H16O)
Opal
Hydrated amorphous silica (SiO2·nH2O)
Precious Opal
SiO2·nH2O (Hydrated Silicon Dioxide)
Amber with Inclusion
Succiniferous fossil resin (C10H16O)
Black Pearl (Tahitian Pearl)
Aragonite / Calcite (CaCO3) with Conchiolin
Obsidian
Obsidian (volcanic glass), primarily SiO2 (silicon dioxide)
Obsidian
Volcanic glass (mainly SiO2 with inclusions)
Mahogany Obsidian
Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)
Obsidian
Obsidian (Volcanic Glass)
Limonite (Iron Stone/Ocher)
Limonite (FeO(OH)·nH2O)
Obsidian
Amorphous volcanic glass (primarily SiO2)
Limonite/Goethite on Shale
Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions (70–75% SiO2)
Black Obsidian
Obsidian (Amorphous Silicon Dioxide)
Snowflake Obsidian
Volcanic Glass with Cristobalite Inclusions
Shungite
Shungite (carbon-rich Precambrian mineraloid)
Common Opal in Host Rock
Hydrated Silica (SiO2·nH2O)
Common Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Obsidian
Obsidian (Volcanic Glass)
Mahogany Obsidian
Obsidian (volcanic glass with hematite/magnetite inclusions)
Black Obsidian
Obsidian (Volcanic Glass, SiO2+)
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2)
Limonite (Yellow Ochre)
Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)
Black Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Limonite (Yellow Ochre)
Limonite (Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O)
Limonite/Goethite Concretion
Hydrated Iron(III) Oxide-hydroxide (FeO(OH)·nH2O)
Obsidian
Obsidian (Volcanic Glass)