Black Onyx
Black Chalcedony (SiO2)
mineral
Category
Amorphous Solid
Browse amorphous solid specimens identified by the Rock Identifier community.
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Agatized Petrified Wood
Silicon Dioxide (SiO2) - Chalcedony pseudomorph after Wood
metamorphic
Megalodon Shark Tooth
Otodus megalodon
fossil
Bowling Ball (Brunswick T-Zone Deep Space)
Polyester resin / Polyurethane polymer
Synthetic (not a natural rock)
Vesicular Basalt / Lava Rock
Extrusive mafic igneous rock (Mafic silicate)
igneous
Red Jasper
Silicon Dioxide (SiO2) with Hematite impurities
sedimentary
Red Jasper (Tumbled)
Silicon Dioxide (SiO2)
sedimentary
Amethyst Geode
Amethyst (Silicon Dioxide), Formula: SiO2
mineral
Likely gold-colored metal ring with a possible gemstone
Uncertain; possibly gold alloy (Au) with a small quartz or glass-like setting
mineral
Black Onyx
Cryptocrystalline Quartz (SiO2) with impurities
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartzite Pebble (River Rock)
Quartzite (primarily SiO2)
metamorphic
Quartzite (Iron-stained)
Quartzite (SiO2 with Fe2O3 staining)
metamorphic
Quartzite
Quartzite (Primary mineral: SiO2)
metamorphic
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartz-veined Mudstone or Argillite
SiO2 (Quartz) in Siltstone/Mudstone matrix
sedimentary
Tumbled yellow-green stone, likely serpentine
Serpentine-group minerals, commonly antigorite/lizardite (Mg₃Si₂O₅(OH)₄)
metamorphic
Quartz Vein in Siltstone
Siltstone with Quartz (SiO2) inclusion
sedimentary
Pearl-and-gemstone insect brooch
Pearl: nacre (aragonite, CaCO₃); colored stones are likely synthetic or natural corundum/spinel/glass, not determinable from the image
gemstone
Garnet Schist
Almandine Garnet-bearing Mica Schist
metamorphic
Banded Gneiss
Gneiss (High-grade regional metamorphic rock)
metamorphic
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartzite
Quartzite (Silicon dioxide, SiO2)
metamorphic
Fossiliferous limestone
Bioclastic limestone, primarily calcite (CaCO₃)
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Sandstone
Arenite (SiO2 based with various mineral cements)
sedimentary
Red Quartzite
Quartzite (SiO2 with iron oxide impurities)
metamorphic
Geode (Unopened)
Siliceous Concretion / Geode
sedimentary
Black Tourmaline in Quartz
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4) in Quartz (SiO2)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Agate (Slab)
Agate (Cryptocrystalline variety of Quartz, SiO2)
Mineral
Gold Nuggests
Native Gold (Au)
mineral
Quartz Geode Fragment
Silicon Dioxide (SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Botryoidal Chalcedony (Agate)
Cryptocrystalline Quartz (SiO2)
mineral
Chondrite Meteorite
Ordinary Chondrite (Fe-Ni alloy, Olivine, Pyroxene)
Mineral
Gray Agate
Cryptocrystalline Quartz (SiO2)
mineral
Black Onyx
Silicon Dioxide (SiO2) - Chalcedony variety
gemstone
Bronzite
MgSiO3 (Enstatite with 10-30% FeSiO3 in solid solution)
Mineral
Fossil coral (likely honeycomb or tabulate coral)
Fossilized colonial coral; possibly Favositidae (Favosites) or related tabulate coral
fossil
Brecciated quartzite (likely iron-stained quartz vein material)
Quartzite; predominantly quartz (SiO₂), with dark iron/manganese-oxide or mica-rich seams
metamorphic
Petrified Wood
Silicified Wood (Quartzo-feldspathic fossil wood)
fossil