Sandstone Concretion
Sedimentary Concretion (Quartz sand bound by mineral cement)
sedimentary
Category
Man Made Byproduct (Often Mistaken For Obsidian Or Emerald)
Browse man made byproduct (often mistaken for obsidian or emerald) specimens identified by the Rock Identifier community.
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Peridot
Olivine ((Mg, Fe)2SiO4)
mineral
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite/Magnetite inclusions)
igneous
Ferruginous Sandstone
Sandstone, Iron-rich
sedimentary
Granite
Granite (composed primarily of Quartz, Feldspar, and Mica/Amphibole)
igneous
Slag (Industrial Glass Slag)
Amorphous Silicate Glass (often containing Al, Ca, Mg, and Ti oxides)
Mineraloid (Industrial byproduct)
Granite River Rock
Phaneritic Felsic Igneous Rock (Granite)
igneous
Greenstone
Greenschist (composed of chlorite, actinolite, and epidote)
metamorphic
Likely weathered iron-rich rock or slag fragment
Uncertain; possibly limonite/goethite-rich material (FeO(OH)·nH₂O)
mineral
Coal
Carbonaceous sedimentary rock
sedimentary
Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Slag Glass (Cullet Glass)
Amorphous Silica (Industrial byproduct)
mineral
Green Fluorite
Calcium Fluoride (CaF2)
mineral
Obsidian
Volcanic Glass
igneous
Dark polished stone, likely basalt or slag-like volcanic rock
Probable fine-grained basalt; exact identification requires testing
igneous
Fluorite (Fluor-spar)
Calcium Fluoride (CaF2)
mineral
Olivine (Peridot when gem-quality)
Magnesium Iron Silicate (Mg,Fe)2SiO4
mineral
Fluorite (Purple/Blue variety)
Calcium Fluoride (CaF2)
mineral
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Igneous
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Granite
Granite (Felsic Plutonic Rock)
igneous
Peridot
Olivine (Magnesium Iron Silicate), (Mg, Fe)2SiO4
mineral
Gold
Native Gold (Au)
mineral
Obsidian
Volcanic Glass (SiO2 - Silicon Dioxide with impurities)
igneous
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
mineral
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)3(Si, Al, Fe)2O5(OH)4
metamorphic
Obsidian
Volcanic glass (high silica content based on SiO2)
igneous
Obsidian
Volcanic glass
igneous
Emerald / Fluorite
Beryl (Be3Al2Si6O18) / Fluorite (CaF2)
mineral
Emerald (Rough)
Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)
gemstone
Granite
Granite (Felsic Plutonic Rock)
igneous
Quartz
Quartz (SiO₂)
Mineral
Chert (Arrowhead Debitage or Spall)
Silicon Dioxide (SiO₂)
sedimentary
Emerald and Diamond (Jewelry Setting)
Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities) and Carbon (C)
mineral
Green Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Polished black stone egg, probably black obsidian
Obsidian, a natural volcanic glass; composition primarily silica-rich glass (approximately SiO₂), with variable iron and other trace elements
gemstone
Peridot (Olivine)
Magnesium Iron Silicate (Mg, Fe)2SiO4
mineral
Green Fluorite
Calcium Fluoride (CaF2)
mineral
Turquoise
Turquoise (Hydrated copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O)
Mineral
Amethyst (Tumbled Cabinet Stone)
Silicon Dioxide (SiO2) with iron impurities
mineral
Greenstone
Greenschist (metamorphosed mafic igneous rock)
metamorphic
Scoria (Lava Rock)
Scoria
igneous