Fossil Crab
Decapoda (likely Avitelmessus or Raninidae family)
sedimentary
Category
Mineral Based Alloy (Anthropogenic)
Browse mineral based alloy (anthropogenic) specimens identified by the Rock Identifier community.
Limestone (specifically Dolomitic Limestone)
Calcium Magnesium Carbonate (CaMg(CO3)2)
sedimentary
Schist
Schist (Crystalline metamorphic rock)
metamorphic
Fired Clay Brick (Anthropic Rock substitute)
Anthropogenic polycrystalline ceramic (predominantly Mullite and Quartz: Al6Si2O13 + SiO2)
metamorphic (man-made / anthropic)
Silver (Native Element)
Ag (Argentum) - 90% Silver, 10% Copper alloy in specimen
mineral
Quartzite Pebble
Quartzite (primarily SiO2)
metamorphic
Gold Ore in Quartz/Matrix
Native Gold (Au) in Quartz (SiO2) matrix
mineral
Chert (Chert Nodule)
Microcrystalline quartz (SiO2)
sedimentary
Granite
Phaneritic Plutonic Igneous Rock (composed of quartz, alkali feldspar, and plagioclase)
igneous
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Conglomerate
Conglomerate (Clastic sedimentary rock)
sedimentary
Textile (Upholstery Fabric)
Woven Polyethylene/Polyester or Cotton Blend
Synthetic or Natural Fiber
Fossil Coral
Cnidaria Anthozoa (Fossilized)
sedimentary
Ambergris
Ambrein (C30H52O Derivative)
Organic (Zoogenic)
Man-made Jewelry (Metal and Glass/Plastic)
Synthetic Alloy and Amorphous Solid (SiO2/Polymer)
not a rock
Gold Ore
Native Gold (Au)
mineral
Gold Nugget
Native Gold (Au)
mineral
Obsidian Arrowhead
Volcanic Glass (Primary composition: SiO2)
igneous
Chert
Chert (Microcrystalline Silica, SiO2)
sedimentary
Gold Nugget / Flake
Native Gold (Au)
mineral
Turquenite (Dyed Howlite)
Dyed Ca2B5SiO9(OH)5 (Calcium Borosilicate Hydroxide)
mineral
Fossilized Turritella Gastropod (Internal Mold)
Turritella (Fossil Gastropod Crust)
sedimentary
Mahogany Obsidian
Volcanic glass containing Magnetite/Hematite
igneous
Banded Calcite (often sold as Onyx Marble)
Calcite (Calcium Carbonate, CaCO3)
sedimentary
Basalt (with Brass Inlay)
Basalt (Mafic volcanic rock)
igneous
Orange Quartzite (Tumble-polished)
Quartzite (primarily SiO2)
metamorphic
Slate
Phyllo-silicate based metamorphic rock
metamorphic
Anthracite Coal
Anthracite (Carbon-based metamorphic rock)
metamorphic
Bituminous Coal
Organic Sedimentary Rock (Carbon-based)
sedimentary
Opalite
Synthetic Opalised Glass
Mineral (Synthetic / Man-made)
Amethyst
SiO2 (Silicon Dioxide)
Mineral
Epidote (Unakite variety)
Epidosite (Metasomatic rock containing Ca2(Al,Fe)3(SiO4)3(OH))
metamorphic
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Pebble (likely Sandstone or Granitic Pebble)
Clastic Sediment (or specific rock type, e.g., Arenite, Granitoid Pebble)
Rock (likely Sedimentary)
Anthracite
Anthracite (highest-grade coal)
metamorphic
Sandstone (specifically Double Arch in Arches National Park)
Entrada Sandstone
sedimentary
Fossilized Coral (Petoskey Stone or similar Favosites)
Hexagonaria percarinata / Favosites (Silurian-Devonian Coral)
sedimentary
Iron Meteorite
Iron Meteorite (primarily Kamacite and Taenite, Fe-Ni alloys)
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Bumble Bee Jasper
Volcanic Tuff (mixture of SiO2, CaCo3, S, and As2S3)
igneous
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Echinoid Fossil (Commonly called a Sea Urchin or Heart Urchin)
Phylum Echinodermata, Class Echinoidea
sedimentary