Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
Category
Browse synthetic or natural fiber specimens identified by the Rock Identifier community.
Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
Orange Quartzite
Quartzite (primarily SiO2 with Hematite impurities)
Pink Anthracite Coal (dyed)
Anthracite Coal (Artificially Colored)
Yellow Aventurine
Quartzite with inclusions (SiO2)
Chert (Jasper variety) with Iron Oxide staining
Cryptocrystalline Quartz (SiO2) with Goethite/Limonite impurities
Yellow Quartz (Citrine Quartz Pebble)
Silicon Dioxide (SiO2)
Water and Silt (Sedimentary Environment)
Suspended Sediment / H2O (dihydrogen monoxide)
Ferruginous Sandstone (Ironstone Nodules)
Ferruginous Quartz-Arenite (with Goethite/Hematite cement)
Gold
Native Gold (Au)
Sandstone
Sandstone (lithified sand)
Yellow Agate
Chalcedony (cryptocrystalline Quartz), SiO2
Quartz (Clear / Rock Crystal)
Silicon Dioxide (SiO2)
Carnelian
Cryptocrystalline Quartz (SiO2 with iron oxide impurities)
Amber
Succinite (specifically for Baltic amber); approximate formula C10H16O
Baroque Pearl
Calcium Carbonate (Aragonite or Calcite) and Conchiolin
Quartz (likely a macrocrystalline variety like milky quartz or smoky quartz, given the appearance in the image)
Quartz (SiO₂ - Silicon Dioxide)
Schist (Kyanite Schist)
Kyanite-Mica Schist (primarily Al2SiO5, KAl2(AlSi3O10)(OH)2, and SiO2)
Diamond
Diamond (Carbon, C)
Turquoise
Hydrated phosphate of copper and aluminum, CuAl6(PO4)4(OH)8·4H2O
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Turquoise (Blue Howlite imitation)
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Clear Quartz
Silicon Dioxide (SiO2)
Fluorite-Gedrite in Quartz (Schist)
Fluorite (CaF2) with Gedrite in Quartz/Feldspar Matrix
Granite
Phaneritic Igneous Rock (primarily Quartz, Feldspar, and Mica)
Grooved Maun Ball (Maul/Hammerstone-like Concretion)
Calcareous/Ferruginous Concretion in Sandstone Matrix
Basalt
Basalt (Mafic Aphanitic Igneous Rock)
Green Aventurine
Quartz (SiO2) with Fuchsite inclusions
Quartz Druze (on Matrix)
Silicon Dioxide (SiO2)
Turquoise
CuAl6(PO4)4(OH)8·4H2O (Hydrous phosphate of copper and aluminium)
Diamond
Diamond (C)
Smoky Quartz
Quartz (SiO₂)
Agate (various color varieties)
SiO₂ (Silicon Dioxide)
Gold Nugget
Native Gold (Au)
Turquoise
CuAl6(PO4)4(OH)8·4H2O
Apache Tear (Obsidian)
Volcanic glass (SiO2 - Silicon Dioxide)
Grey Slate
Foliated Metamorphic Rock (formed by low-grade regional metamorphism of shale or mudstone)
Gold Nugget
Native Gold (Au)
Smoky Quartz
Silicon Dioxide (SiO2)
Bismuth
Bismuth (Bi)
Turquoise
CuAl6(PO4)4(OH)8·4H2O (Hydrous phosphate of copper and aluminium)
Selenite (Satin Spar)
Gypsum (CaSO4·2H2O)
Hematite Beads
Hematite (Fe2O3)