Coal (Bituminous Coal)
Caustobiolith / Sedimentary Rock
sedimentary
Category
Antropogenic Rock (Man Made)
Browse antropogenic rock (man made) specimens identified by the Rock Identifier community.
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Weathered concrete or cementitious slab (not natural rock)
Artificial calcium-silicate cement composite; likely Portland cement concrete
sedimentary
Chert (Flint/Jasper variety)
Microcrystalline Quartz (SiO2)
sedimentary
Sandstone Concretion
Sedimentary concretion
Sedimentary
Jewelry Chain with Blue and Clear Gemstones (Likely Cubic Zirconia)
Cubic Zirconia (ZrO₂), Silver or White Gold/Platinum Alloy
Mineral (synthetic) and Metal (precious/base)
Granite
Granite (a plutonic rock)
Igneous
Chert
Chert (Microcrystalline Quartz)
sedimentary
Siltstone Pebble
Siltstone (composed of microscopic quartz and clay minerals)
sedimentary
Granite
Granite (composed primarily of Quartz, Feldspar, and Mica)
igneous
Man-made Green Quartz (Lab-grown or Treated)
Silicon Dioxide (SiO2) with artificial coloration
mineral
Greenstone
Metabasalt / Metavolcanic rock
metamorphic
Chert (Flint)
Silicon dioxide (SiO2)
sedimentary
Goldstone (aventurine glass)
Synthetic copper-bearing soda-lime glass; commonly sold as red goldstone
gemstone
Vesicular Basalt (or Scoria)
Vesicular Basalt
igneous
Pumice
Pumice (Vesicular volcanic glass)
Igneous
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Sandstone
Arenite
sedimentary
Beaded gemstone bracelet
Indeterminate; likely small polished mineral beads, possibly turquoise or dyed stone, with metal and glass components
gemstone
Desert Rose (Gypsum Rose)
Calcium Sulfate Dihydrate (CaSO4·2H2O)
mineral
Granodiorite
Phaneritic Plutonic Intermediate-Felsic Rock
igneous
Exposed aggregate concrete (stone-chip surface)
Portland-cement concrete containing natural aggregate; not a natural rock
sedimentary
Chert Arrowhead
Cryptocrystalline Quartz (SiO2)
sedimentary
Ferrous Slag (Iron Smelting By-product)
Fused Siliceous Slag
Anthropogenic Material (Man-made Rock)
Quartz Pebble (Beach Chalcedony)
Silicon Dioxide (SiO2)
mineral
Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary
Turquoise ring
Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O; the setting appears to be silver-colored metal
gemstone
Small clear crystal, possibly quartz or glass-like gemstone
Uncertain; likely quartz (SiO₂), but the image is insufficient to exclude man-made glass or cubic zirconia
mineral
Sandstone
Arenite
sedimentary
Blue glass-like bead or gemstone keychain ornament
Indeterminate; likely cobalt-blue glass or synthetic blue spinel, not identifiable as a natural mineral from the image
gemstone
Belemnoit (Fossil)
Belemnoidea (Order), Rostrum / Guard
sedimentary
Polished stone sphere, possibly agate or jasper
Likely microcrystalline quartz (SiO₂); exact variety cannot be confirmed from the image
mineral
Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary
Chert (White Chert/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Yellow cabochon gemstone, likely citrine or yellow glass imitation
Quartz (SiO₂), if natural citrine; visual evidence is insufficient to exclude man-made glass or resin
gemstone
Polished green-and-black banded cabochon (likely malachite imitation or dyed agate)
Uncertain; possible malachite (Cu₂CO₃(OH)₂), banded agate (SiO₂), or man-made glass
gemstone
Polished blue-green glassy slag or coated mineral fragment
Most likely man-made colored glass/slag; exact composition cannot be determined visually
mineral
Asphalt Chunk (with aggregate)
Bituminous concrete / Anthropogenic conglomerate
sedimentary (anthropogenic/man-made conglomerate)
Slate
Metamorphic Pelitic Rock
metamorphic
Slate
Metamorphic Pelitic Rock
metamorphic
Green glassy slag (often sold as “sea glass” or “green obsidian”)
Industrial vitreous slag; primarily amorphous silicate glass, composition variable
mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone (Quartzose)
Arenite (composed primarily of SiO2)
sedimentary