Obsidian
Volcanic Glass (felsic composition)
igneous
Category
Mineraloid (Man Made Glass)
Browse mineraloid (man made glass) specimens identified by the Rock Identifier community.
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Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Mahogany Obsidian
Volcanic glass containing Magnetite/Hematite
igneous
Sea Glass
Amorphous silicon dioxide (glass)
mineral
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)
igneous
Limonite or Ironstone Nodule
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
sedimentary
Black Opal (Triplet)
Hydrated Silica (SiO2·nH2O)
mineral
Obsidian
Volcanic Glass (Amorphous SiO2)
igneous
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Obsidian
Volcanic glass (Amorphous silicon dioxide)
igneous
Limonite (Iron Ore)
Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)
Mineral
Mahogany Obsidian
Obsidian (volcanic glass with hematite/magnetite inclusions)
igneous
Mahogany Obsidian
Volcanic glass (SiO2 + Fe2O3)
igneous
Obsidian
Volcanic Glass (predominantly SiO2, approximately 70% or more)
igneous
Obsidian
Volcanic Glass (70% or more SiO2)
igneous
Green Aventurine
Silicon Dioxide (SiO2) with inclusions of Fuchsite
metamorphic
Aventurine
Silicon Dioxide (SiO2) with inclusions of Fuchsite
mineral
Metal Chain (Likely Steel or a Steel Alloy)
Steel (primarily iron and carbon); specific alloy unknown
Man-made Object (Metal/Alloy)
Diamond (or Diamond Simulant)
Carbon (C) or Cubic Zirconia (ZrO2)
gemstone
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
mineral
Black Obsidian
Volcanic glass (Amorphous silicates)
igneous
Blue Goldstone
Aventurine Glass (Silicon Dioxide infused with Cobalt/Copper)
Synthetic (Man-made Glass)
Obsidian
Volcanic glass (silica-rich rhyolitic melt; primarily SiO₂)
igneous
Sea Glass (Cobalt Blue)
Amorphous Silica (Glass with Cobalt additives)
Anthropogenic specimen (man-made)
Chert (Flint)
Silicon dioxide (SiO2)
sedimentary
Anthracite Coal
Anthracite (Carbon-rich mineraloid)
metamorphic
Amber
Succinite (Organic Mineraloid) - C10H16O
mineral
Obsidian
Volcanic Glass (comprised primarily of SiO2)
Igneous
Pumice
Pumice (Vesicular volcanic glass)
Igneous
Limonite (Ironstone)
Limonite (mixture of hydrated iron oxides, primarily Goethite α-FeO(OH))
mineral
White Opal
Hydrated Silica (SiO2·nH2O)
mineral
Chert (specifically Tan/Gray Chert)
Microcrystalline quartz (SiO2)
sedimentary
Pumice
Pumice (Vitreous volcanic rock)
igneous
Blue Sea Glass
Amorphous Silica (Anthropogenic glass)
not a rock (man-made origin)
Black Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
igneous
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
igneous
Mahogany Obsidian
Volcanic Glass (SiO2 with Fe/Mg oxides)
igneous
Tektite (likely Australite)
Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)
Mineral (specifically a mineraloid)
Chert (Flint/Jasper variety)
Microcrystalline Quartz (SiO2)
sedimentary
Man-made Metal Pin (Non-geological)
Antimony-Lead Alloy or Zinc/Brass Base with Electroplating
Metal Alloy / Manufactured Artifact
Pearl
Organic Mineraloid (CaCO3 + Conchiolin)
mineral
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous