Peridot
Olivine (Magnesium Iron Silicate), (Mg, Fe)2SiO4
mineral
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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Obsidian
Volcanic glass
igneous
Chert (Arrowhead Debitage or Spall)
Silicon Dioxide (SiO₂)
sedimentary
Mahogany Obsidian
Volcanic glass (SiO2 with Hematite/Magnetite inclusions)
igneous
Green Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Emerald and Diamond (Jewelry Setting)
Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities) and Carbon (C)
mineral
Green Fluorite
Calcium Fluoride (CaF2)
mineral
Pyrite (fool’s gold)
Pyrite, FeS₂
mineral
Iron Slag
Iron smelting byproduct (Glassy/vesicular silicate)
anthropogenic / industrial byproduct
Peridot (Olivine)
Magnesium Iron Silicate (Mg, Fe)2SiO4
mineral
Manganese Oxide Crust on Limestone
Manganese Oxides (e.g., Pyrolusite MnO2 or Romanechite) on CaCO3
sedimentary
Greenstone
Greenschist (metamorphosed mafic igneous rock)
metamorphic
Scoria (Lava Rock)
Scoria
igneous
Chert
Chert (Microcrystalline Quartz)
sedimentary
Dendritic Siltstone
Siltstone with Manganese Oxide dendrites (MnO2)
sedimentary
Granite
Granite (Felsic Plutonic Rock)
igneous
Dark polished stone, likely basalt or slag-like volcanic rock
Probable fine-grained basalt; exact identification requires testing
igneous
Blue Obsidian
Obsidian
igneous
Green Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Carved smoky quartz (likely)
Quartz, silicon dioxide (SiO₂), smoky variety
mineral
Fuchsite (Green Muscovite in Quartz)
K(Al,Cr)2(AlSi3O10)(OH)2 - Chromium-rich Muscovite
metamorphic
Prehnite
Prehnite, Ca2Al(AlSi3O10)(OH)2
mineral
Green Fluorite in Host Rock
Fluorite (Calcium Fluoride, CaF2)
mineral
Ferruginous Sandstone
Sandstone, Iron-rich
sedimentary
Concretion in Shale
Siltstone/Shale with Siderite or Calcareous concretions
sedimentary
Emerald
Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)
gemstone
Green Fluorite
Fluorite (Calcium Fluoride - CaF2)
mineral
Emerald-and-diamond ring
Emerald: beryl, Be₃Al₂(SiO₃)₆, colored by chromium and/or vanadium; surrounding stones appear to be diamonds: carbon
gemstone
Siltstone
Siltstone (Detrital Sedimentary Rock)
sedimentary
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
Green Fluorite
Calcium Fluoride (CaF2)
mineral
Emerald
Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities
gemstone
Peridot
Olivine (Mg, Fe)₂SiO₄
mineral
Peridot (Olivine)
Magnesium Iron Silicate (Mg,Fe)2SiO4
mineral
Granite
Granite (Felsic Plutonic Rock)
igneous
Green Fluorite
Calcium Fluoride (CaF2)
mineral
Peridot
Olivine ((Mg, Fe)2SiO4)
gemstone
Sandstone with Manganese Dendrites
Arenite (mostly SiO2) with Manganese Oxide inclusions (MnO2)
sedimentary
Obsidian
Obsidian (volcanic glass)
igneous
Amethyst (Tumbled Cabinet Stone)
Silicon Dioxide (SiO2) with iron impurities
mineral
Faceted Peach Morganite (Beryl)
Morganite (Be3Al2Si6O18 with trace Manganese)
mineral