Sandstone (Banded)
Clastic Sedimentary Rock (primarily SiO2)
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Sandstone (Banded)
Clastic Sedimentary Rock (primarily SiO2)
Milky Quartz
Quartz (SiO2) with iron staining
Red Garnet (Pyrope or Almandine)
Magnesium aluminum silicate (Mg3Al2(SiO4)3) or Iron aluminum silicate (Fe3Al2(SiO4)3)
Honey Calcite
Calcium Carbonate (CaCO3)
Garnet (specifically Almandine or Pyrope)
Almandine: Fe3Al2(SiO4)3 or Pyrope: Mg3Al2(SiO4)3
Rose Quartz
SiO2 (Silicon Dioxide)
Greenstone
Protolith of basalt, diabase, or gabbro; often contains minerals like chlorite, actinolite, and epidote
Granite (Core Sample)
Phaneritic Felsic Igneous Rock (Granite)
Gold-bearing Quartz with Pyrite
Quartz (SiO2) with Gold (Au) and Pyrite (FeS2)
Kyanite
Kyanite (Al2SiO5)
Sandstone
Arenite (composed primarily of SiO2)
Fluorite
Calcium fluoride (CaF2)
Limonite (Oxidized Iron Ore)
FeO(OH)·nH2O (Hydrous ferric oxide)
Quartz on Limestone
Silicon Dioxide (SiO2) on Calcium Carbonate (CaCO3)
Quartz with Mica/Host Rock
Silicon Dioxide (SiO2) with Phyllosilicates
Quartz (Citrine or Iron-Stained)
Silicon Dioxide (SiO2)
Granitic Pegmatite
Coarse-grained Granite (KAlSi3O8 + SiO2)
Limonite with Galena
FeO(OH)·nH2O (Limonite) and PbS (Galena)
Chalcedony (specifically Agate or Flint)
Silicon Dioxide (SiO₂)
Limonite/Ironstone
Limonite (FeO(OH)·nH2O)
Green Fluorite
Fluorite (Calcium Fluoride, CaF2)
Fossil Coral
Fossilized Scleractinia or Tabulata (various genera/species)
Fuchsite
K(Al,Cr)2(AlSi3O10)(OH)2
Magnetite
Magnetite (Fe3O4)
Fluorite
Calcium Fluoride (CaF2)
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrous ferric oxide)
Quartz (Druzy Quartz)
Silicon Dioxide (SiO2)
Rough Diamond
Diamond (Native Carbon), C
Rough Diamond
Diamond (pure Carbon, C)
Diamond (faceted)
Diamond (Pure Carbon, C)
Lepidolite
Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)
Lepidolite
Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)
Blue Kyanite
Kyanite (Al2SiO5)
Basalt
Basalt (Mafic volcanic rock)
Amber
Fossilized tree resin (not a true mineral as it is organic and amorphous); Chemical formula is highly variable, but often approximated as C10H16O.
Micaceous Rock (likely Muscovite Schist/Gneiss or a Muscovite-rich Specimen)
Predominantly Muscovite (KAl2(AlSi3O10)(F,OH)2), often found in rocks like Muscovite Schist or Muscovite Gneiss.
Lepidolite
K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2 (Lithium-bearing Phyllosilicate)
Sapphire (likely blue synthetic sapphire or blue glass in a ring)
Corundum (Al₂O₃), specifically the blue variety due to trace amounts of iron and titanium impurities. If synthetic, it would still be Al₂O₃.
Fluorite
Calcium Fluoride (CaF2)
Mica Schist
Mica Schist (KAl2(AlSi3O10)(OH)2 - Muscovite component)
Turquoise
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Sulfur on Quartz
Native Sulfur (S8) with Quartz (SiO2)