Diabase (Dolerite)
Diabase / Dolerite
igneous
Category
Mineraloid (Man Made)
Browse mineraloid (man made) specimens identified by the Rock Identifier community.
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Land Snail Shell
Gastropoda (Calcium Carbonate, CaCO3)
fossil
Blue glass-like tumbled specimen
Most likely cobalt-blue slag glass or manufactured glass; not confidently identifiable as a natural mineral from the image
mineral
Sandstone
Arenite
sedimentary
Quartzite
Metamorphic Quartz Sandstone
metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Dark quartz point (possibly smoky quartz)
Quartz, SiO₂; the dark color may indicate smoky quartz, but the image is insufficient to confirm
mineral
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Sandstone (Pebble)
Sandstone (arenite, arkose, wacke depending on composition)
sedimentary
Jasper
Silicon dioxide (SiO2) with impurities
sedimentary
Quartzite
Metamorphic Rock (Mainly SiO2)
metamorphic
Obsidian (Black)
Obsidian (High-silica volcanic glass)
igneous
Fossil crinoid columnal in limestone
Crinoidea indet.; calcitic ossicle (CaCO₃)
fossil
Diabase (Greenstone)
Diabase (Dolerite)
igneous
Sandstone
Arenite
sedimentary
Turquoise cabochon ring
Turquoise — hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O
gemstone
Jade bangle
Likely nephrite jade (actinolite–tremolite amphibole); possibly jadeite
gemstone
Sandstone (specifically Arkose or Quartz Arenite)
Arenite (primarily SiO2 with possible Feldspar)
sedimentary
Limestone
Calcareous sedimentary rock (CaCO3)
sedimentary
Red Sandstone
Arenite (with Iron Oxide / Hematite staining)
sedimentary
Ferruginous Sandstone (Ironstone)
Clastic Sedimentary Rock (composed of SiO2 with Fe2O3/FeO(OH) cement)
sedimentary
Fossilized sea urchin
Echinoid test, likely a regular sea urchin; calcite (CaCO₃)
fossil
Fossilized echinoid (sea urchin), likely a sand dollar fragment or small regular urchin
Echinodermata; commonly Clypeasteroida or Echinoida, preserved mainly as calcite (CaCO₃)
fossil
Weathered iron-rich rock, possibly jasper or ironstone
Likely limonite/goethite-bearing siliceous rock; exact identification requires hardness and streak tests
mineral
Dyed Blue Agate Slice
Silicon Dioxide (SiO2)
mineral
Quartzite Pebble
Quartzite (SiO2)
metamorphic
Banded Calcite or Travertine
Calcium Carbonate (CaCO3)
Sedimentary
Coral Rock (Coquina)
Biogenic Limestone (Calcium Carbonate - CaCO3)
sedimentary
Weathered, rounded polymictic pebble (likely volcanic or metamorphic rock)
Indeterminate; possibly altered basalt, greenstone, or epidote-bearing metamorphic rock
igneous
Amber with Inclusion
Succiniferous fossil resin (C10H16O)
mineraloid
Granite
Granite (felsic intrusive igneous rock)
igneous
Jade
Jadeite or Nephrite
Mineral/Mineraloid
Garnet Beads
Garnet Group (complex nesosilicates, e.g., Almandine Fe3Al2(SiO4)3)
Mineral
Limonite (Iron Ore)
Hydrous Iron Oxide (goethite, lepidocrocite)
Mineral
Granite Cobble/Pebble
Granite
Igneous
Granite
Granite (a common rock type, not a single mineral with a formula. Composed primarily of quartz, feldspar, and mica/amphibole).
igneous
Likely obsidian (possibly tektite or slag glass)
Volcanic glass; primarily SiO₂, noncrystalline
igneous
Granite
Granite (a plutonic rock)
Igneous
Pearl
Organic Mineraloid (CaCO3 + Conchiolin)
mineral
Bog Iron / Limonite Concretion
Goethite/Limonite mixture (FeO(OH)·nH2O)
sedimentary
Crushed Limestone
Calcium Carbonate (CaCO3)
Sedimentary