Obsidian
Volcanic glass
Category
Browse mineraloid (human made geological specimen) specimens identified by the Rock Identifier community.
Obsidian
Volcanic glass
Slag Glass (Cullet)
Amorphous Silica (man-made), primarily SiO2 with trace metal oxides
Diorite (River Pebble)
Intermediate Phaneritic Igneous Rock
Opalite (Man-made Glass)
Synthetic Silicon Dioxide Glass (SiO2 + metal oxides)
Opalite
Man-made Synthetic Glass (Silicon Dioxide with metal additives)
Sandstone
Clastic Sedimentary Rock
Quartzite
Quartzite (primarily SiO2)
Granite, possibly granodiorite
Coarse-grained felsic plutonic rock; chiefly quartz (SiO₂), potassium feldspar and plagioclase feldspar, with biotite and/or hornblende
Quartzite (River Pebble)
Quartzite (Mainly SiO2)
Lightning Stone / Fulgurite-impregnated or Septarian-like Agate
Silicon dioxide (Quartz/Chalcedony) with host rock matrix
Quartzite
Quartzite (SiO2)
Sandstone (specifically Arkose or Quartz Arenite)
Arenite (primarily SiO2 with possible Feldspar)
Chert (Flint)
Silicon Dioxide (SiO2)
Slag (Industrial Glass)
Artificial Vitreous Silicate
Petoskey Stone
Hexagonaria percarinata (Fossilized Rugose Coral)
Concrete / Conglomerate (Man-made)
Artificial Conglomerate (Cementitious Composite)
Granite
Phaneritic Igneous Rock (composed mostly of Quartz, Feldspar, and Mica)
Pyrite
Iron Disulfide (FeS2)
Amber in Matrix
Succinite (Carbon-based organic polymer)
Chert (Jasper/Flint variety)
Microcrystalline quartz (SiO2)
Chert (River Siltstone/Quartzite type)
Microcrystalline Quartz (SiO2)
Sandstone (likely Quartzose Sandstone)
Arenite
Chert (Jasper)
Microcrystalline Quartz (SiO2)
Sandstone (Pebble)
Arenite
Copper Ore / Altered Granodiorite
Cupriferous rock with silicate gangue
Fossilized Brachiopod Shell
Order Spiriferida (likely)
Goldstone (Brown)
Aventurine glass
Chert (Commonly known as Flint)
Microcrystalline Quartz (SiO2)
Sandstone
Arenite
Iron Slag (Industrial Byproduct)
Anthropogenic Vitrification Product/Ferrous Slag
Limestone
Calcium Carbonate (CaCO3)
Petrified Wood (Silicified Wood)
Silicified Paleoflora (mainly Quartz, SiO2)
Sandstone
Arenite (variable SiO2 composition)
Silver (Jewelry form)
Native Silver (Ag)
Chalcedony (Agate)
Silicon Dioxide (SiO2)
Chert (and/or Flint)
Chert (Cryptocrystalline variety of Quartz, SiO2)
Fossiliferous Chert (with Fossil Shells)
Silicon Dioxide (SiO2) with biogenic inclusions
Sandstone Concretion
Clastic Sedimentary Rock (primarily SiO2 with mineral cement)
Obsidian
Volcanic Glass (70% or more SiO2)
Polished serpentine
Serpentine-group minerals, chiefly lizardite and/or antigorite; approximate formula Mg₃Si₂O₅(OH)₄
Pink Quartz / Sea Glass
Silicon Dioxide (SiO2)
Obsidian
Volcanic glass