Carved quartz skull, likely smoky quartz or gray chalcedony
Silicon dioxide (SiO₂), quartz or microcrystalline quartz
gemstone
Category
Mineraloid (Man Made Glass)
Browse mineraloid (man made glass) specimens identified by the Rock Identifier community.
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Sandstone (Pebble)
Sandstone (arenite, arkose, wacke depending on composition)
sedimentary
Fossilized Coral (Coquina/Limestone)
Cnidaria Anthozoa (Fossilized)
sedimentary
Chert (variations include Flint)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Diamond
Diamond (pure Carbon, C)
mineral
Chert (White Chert/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Gypsum (Satin Spar / Alabaster variety)
Calcium Sulfate Dihydrate (CaSO4·2H2O)
mineral
Granite
Plutonic Igneous Rock (composed typically of SiO2, Al2O3, K2O, Na2O, CaO)
igneous
Chert (specifically Yellow/Brown Chert or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
US Penny
Cuprum (Copper: Cu) and Zincum (Zinc: Zn) Alloy
Man-made object (metal alloy)
Pearl-embellished decorative cross
Pearl (biogenic calcium carbonate, predominantly aragonite) with rhinestone-mounted glass or synthetic gemstones
gemstone
Lava Rock (Dyed)
Basalt / Volcanic scoria
igneous
Chert (Flint variety)
Chert (Microcrystalline or Cryptocrystalline Quartz), SiO2
sedimentary
Flint / Chert
Microcrystalline Quartz (SiO2)
sedimentary
Siltstone Pebble
Siltstone (composed of microscopic quartz and clay minerals)
sedimentary
Engineered Quartz (Quartzite look-alike)
Silicon Dioxide (SiO2) composite
mineral-based composite
Granite
Phaneritic Igneous Rock (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)
igneous
Coquina
Biogenic Limestone (Coquina)
sedimentary
Diamond (or Cubic Zirconia)
Carbon (C) or Zirconium Dioxide (ZrO2)
gemstone
Vesicular Basalt (or Scoria)
Vesicular Basalt
igneous
Belemnoit (Fossil)
Belemnoidea (Order), Rostrum / Guard
sedimentary
Granite
Phaneritic Plutonic Felsic Rock
igneous
Granite
Granite (Phaneritic igneous rock)
igneous
Turquoise
Turquoise, CuAl6(PO4)4(OH)8·4H2O
mineral
Diamond
Cubic carbon (C)
mineral
Tumbled brown chalcedony (likely jasper or agate)
Microcrystalline quartz, SiO₂; chalcedony with iron-oxide staining
mineral
Slate
Metamorphic Pelitic Rock
metamorphic
Diamond
Carbon (C)
mineral
Rutilated Quartz
Silicon Dioxide (SiO2) with Titanium Dioxide (TiO2) inclusions
mineral
Granodiorite
Intrusive Igneous Rock
igneous
Granite / Diorite (Granodiorite)
Granodiorite / Quartz Diorite
igneous
Diamond
Diamond (pure carbon C)
mineral
Diamond
Carbon (C)
mineral
Pearl
Calcium Carbonate (CaCO3) - Aragonite/Calcite
mineral
Granodiorite / Granite (Weathered)
Granodiorite
Igneous
Quartz (Engineered Quartz Surface)
Silicon Dioxide (SiO2) based composite
mineral (man-made composite)
Asphalt (Bituminous Concrete)
Bituminous Concrete / Pavement
man-made (synthetic rock)
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Limpets Shell / Fossil Specimen
Patellogastropoda (Class)
fossil
Chalk
Micrite (primarily Calcium Carbonate or CaCO3)
sedimentary
Diabase (Greenstone)
Diabase (also known as Dolerite)
igneous
Obsidian
Obsidian (volcanic glass, amorphous silica rich rock)
Igneous