Obsidian
Obsidian (principally SiO2 with MgO and Fe3O4)
Category
Browse mineraloid (human made geological specimen) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (principally SiO2 with MgO and Fe3O4)
Basalt (Arrowhead form)
Extrusive mafic igneous rock
Chert (Flint variety)
Silicon Dioxide (SiO2)
Chert (specifically Flint or Common Chert node)
Silicon Dioxide (SiO2)
Chert / Jasper
Microcrystalline Quartz (SiO2)
Opalite
Synthetic Opalised Glass
Nickel coin (U.S. currency)
Cupronickel (75% Copper, 25% Nickel alloy)
Sandstone
Arenite (composed primarily of SiO2)
Sea Shell (Fighting Conch Fragment)
Calcium Carbonate (CaCO3) - Strombus alatus fragment
Carnelian
Chalcedony (cryptocrystalline quartz), SiO2
Granite
Phaneritic Igneous Rock (composed mostly of Quartz, Alkali Feldspar, and Plagioclase)
Amber in Matrix
Succinite (Carbon-based organic polymer)
Fossilized Coral (Petoskey-style)
Hexagonaria percarinata (Fossilized Rugose Coral)
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
Obsidian
Volcanic glass
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
Crinoid Fossil Stem Segment
Class Crinoidea (Echinodermata)
N/A (Non-Geological Specimen)
Limonite (Iron Ore)
Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)
Apatite
Fluorapatite, Chlorapatite, and Hydroxylapatite (Ca5(PO4)3(F,Cl,OH))
Aragonite Star Cluster
Aragonite (Calcium Carbonate, CaCO3)
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2 + Fe2O3)
Moqui Marble
Iron Oxide Concretion (Limonite/Hematite shell with Sandstone core)
Fluorite (Polished Point/Tower)
Calcium Fluoride (CaF2)
Malachite
Malachite (Copper Carbonate Hydroxide) - Cu2CO3(OH)2
Diamond (in jewelry setting)
Carbon (C)
Coquina
Bioclastic Limestone
Halite
Sodium Chloride (NaCl)
Sandstone
Clastic sedimentary rock (Quartz arenite/Arkose)
Jade (Nephrite or Jadeite)
Nephrite (Ca2(Mg,Fe)5Si8O22(OH)2) or Jadeite (Na(Al,Fe3+)Si2O6)
Sandstone (likely Fossiliferous)
Arenite / Fossiliferous Sandstone (SiO2 composition)
Gold Ore in Quartz
Auriferous Quartz (Au + SiO2)
Slag (Industrial Glass)
Artificial Vitreous Silicate
Undetermined Due to Blur (Possible Flesh-Tone Mineral)
Unknown (Insufficient Visual Clarity)
Chert (variant of Flint)
Chert (SiO2)
Obsidian
Obsidian (Amorphous volcanic glass, predominantly SiO2)
Chert (Jasper/Agate variety)
Microcrystalline Quartz (SiO2)
Chert (Jasper)
Silicon Dioxide (SiO2) with impurities
Chert / River Jasper
Microcrystalline Quartz (SiO2)
Dyed Quartz Geode
Silicon Dioxide (SiO2) with artificial pigment
Specular Hematite with Quartz and Limonite
Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)