Fossilized Crab Carapace (Concretion)
Decapoda (fossil), typically preserved in calcite or siderite concretion
sedimentary
Category
Mineral Based Human Made Alloy
Browse mineral based human made alloy specimens identified by the Rock Identifier community.
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Mica Schist
Schist (primarily Muscovite and Biotite mica)
metamorphic
Chert with Iron Staining
Microcrystalline quartz (SiO2) with iron oxide inclusions
sedimentary
Jasper
Silicon dioxide (SiO2) with iron oxide inclusions
sedimentary
Bloodstone
Heliotrope (Silicon dioxide, SiO2)
mineral
Silicon Carbide (Carborundum)
Moissanite (SiC), though mostly synthetic
mineral
Heat-Treated Citrine (Amethyst)
Silicon Dioxide (SiO2) with iron impurities
mineral
Mosasaur Tooth Fossil
Mosasauridae (likely Prognathodon or Plioplatecarpus)
fossil
Pearl
Calcium Carbonate (Aragonite) with Conchiolin; formula: CaCO3
mineral
Quartz-veined Sedimentary Rock
Hydrothermally veined Clastic Sedimentary Rock (SiO2 veins in Matrix)
sedimentary
Granite
Intrusive Phaneritic Felsic Igneous Rock
igneous
Sandstone with Iron Staining
Arenite (SiO2 with Fe-oxide coatings)
sedimentary
Quartz with Iron Staining
Silicon Dioxide (SiO2) with Goethite/Limonite inclusions
mineral
Citrine Quartz
Silicon Dioxide (SiO2)
mineral
Tumbled Grey Agate
Silicon Dioxide (Chalcedony variety), SiO2
mineral
Chalcedony (Common Agate)
Silicon Dioxide (SiO2)
mineral
Banded Chalcedony (Agate)
Cryptocrystalline Quartz (SiO2)
mineral
Chalcedony (Agate/Chert)
Microcrystalline Quartz (SiO2)
mineral
Carnelian (Orange Chalcedony)
Silicon Dioxide (SiO2) - variety of Chalcedony
mineral
Carnelian
SiO2 (Silicon Dioxide) with Iron Oxide impurities
mineral
Amethyst Cluster
Silicon Dioxide (Quartz variety: Amethyst) - SiO2
mineral
Sandstone (lithic/greywacke variety)
Arenite (composed primarily of SiO2 with various lithic fragments)
sedimentary
Basalt with Vesicles
Vesicular Basalt (Mafic Extrusive)
igneous
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic Volcanic Rock)
Igneous
Milky Quartz Vein with Iron Staining
Silicon Dioxide (SiO2)
mineral
Basalt and Andesite Gravel
Aphanitic Mafic-Intermediate Volcanic Rock
igneous
Yellow Ochre (Limonite)
Limonite (FeO(OH)wH2O)
sedimentary
Green Fuchsite and Quartz
K(Al,Cr)2(AlSi3O10)(OH)2 (Chromium-rich Muscovite)
metamorphic
Banded Limestone
Calcareous sedimentary rock (CaCO3)
sedimentary
Granite
Granite (composed primarily of Quartz SiO2, Potassium Feldspar KAlSi3O8, and Plagioclase)
igneous
Amygdaloidal Basalt
Extrusive mafic igneous rock with amygdules
igneous
Quartz Druzy on Matrix
Silicon Dioxide (SiO2)
mineral
Fossil Shark Tooth
Carcharadon sp. (likely Carcharodon carcharias or similar Lamniformes)
fossil
Bloodstone
Chalcedony (Variety: Bloodstone / Heliotrope), SiO2
mineral
Fossilized Brain Coral
Diploria labyrinthiformis (Fossilized)
sedimentary
Green Agate
Silicon dioxide (SiO₂)
mineral
Garnet-Bearing Schist
Almandine Garnet Micaceous Schist
metamorphic
Basalt with Olivine (Peridot)
Basalt containing (Mg,Fe)2SiO4
igneous
Basalt with Amygdales
Amygdaloidal Basalt
igneous
Fuchsite
Chromian Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)
mineral
Granite
Phaneritic Plutonic Felsic Rock
igneous