Sandstone (Quartz Arenite)
Sandstone (dominated by SiO2 quartz grains)
sedimentary
Category
Mineral (Man Made Composite)
Browse mineral (man made composite) specimens identified by the Rock Identifier community.
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Fossil Turtle Shell
Testudines carapace fossil
fossil
Granite
Granite (Plutonic Igneous Rock)
igneous
Polished turquoise cabochon jewelry (likely composite or stabilized turquoise)
Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O
mineral
Dumortierite in Quartz
Dumortierite (Al6O3(BO3)(SiO4)3) with Quartz (SiO2)
mineral
Obsidian
Obsidian (Volcanic Glass)
igneous
Diamond
Carbon (C)
gemstone
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Diamond
C (Carbon)
gemstone
Raw Diamond
Carbon (C)
gemstone
Diorite
Intermediate plutonic igneous rock
igneous
Sandstone Pebble
Ferruginous Sandstone (SiO2 with Fe2O3)
sedimentary
Granodiorite
Granodiorite (Quartz + Plagioclase + Alkali Feldspar + Biotite/Hornblende)
igneous
Tumbled green glassy mineral, possibly aventurine or fluorite
Uncertain; likely quartz variety (aventurine quartz, SiO₂) or green fluorite (CaF₂)
mineral
Iron-stained quartz-rich rock, possibly jasper or chert
Microcrystalline quartz (SiO₂) with iron oxides/hydroxides
mineral
Flint (chert) nodule
Microcrystalline quartz (SiO₂), occurring as a flint/chert nodule in limestone
sedimentary
Sandstone
Clastic sedimentary rock (Quartz arenite/Arkose)
sedimentary
Granite
Granite (Felsic Plutonic Rock)
igneous
Blue calcite sphere
Calcite (CaCO₃), commonly blue-calcite variety
mineral
Polished brecciated jasper pendant
Jasper, an opaque microcrystalline variety of chalcedony (mostly SiO₂), with iron-oxide staining and likely brecciation
mineral
Bog Iron / Limonite Concretion
Goethite/Limonite mixture (FeO(OH)·nH2O)
sedimentary
Diamond
Carbon (C)
gemstone
Multicolor quartz bead bracelet
Quartz (silicon dioxide, SiO₂); bead colors may be from different varieties or treated quartz
gemstone
Granite
Phaneritic plutonic rock (Quartz, Feldspar, Mica)
igneous
Diamond in Kimberlite
Diamond in Kimberlite Matrix (Diamond: C, Kimberlite: complex Potassic Peridotite)
igneous
Granite
Phaneritic Felsic Igneous Rock
igneous
Smoky Quartz
Silicon Dioxide (SiO2) with trace aluminum and irradiation
mineral
Swirled Agate Bead
Silicon Dioxide (SiO2)
mineral
Rough Diamond
Diamond (pure Carbon, C)
mineral
Natural Pearl (appearing in a jewelry setting)
Calcium Carbonate (mostly Aragonite), CaCO3 with Conchiolin
mineral
Amethyst (Tumbled Cabinet Stone)
Silicon Dioxide (SiO2) with iron impurities
mineral
Diamond
Native Carbon (C)
mineral
Geode (Unopened)
Quartz Geode (SiO2) / Chalcedony Concretion
mineral
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (70–75% SiO2)
igneous
Weathered fossil shell fragment
Indeterminate bioclastic carbonate, likely molluscan shell (calcium carbonate, commonly aragonite or calcite)
fossil
Pearl and Garnet Glass
Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass
mineral and glass
Cullet Glass (Strawberry Glass)
Amorphous Silicon Dioxide (SiO2) with metallic dopants
Mineraloid (Synthetic/Man-made)
Diamond
Diamond (pure Carbon, C)
mineral
Granite
Granite (a phaneritic intrusive igneous rock)
igneous
Concrete-like aggregate surface with embedded rock fragments
Anthropogenic concrete or exposed aggregate; not a natural rock specimen
sedimentary
Tumbled gray chalcedony (likely agate or quartzite)
Microcrystalline quartz, SiO₂ (chalcedony)
mineral
Likely weathered iron-rich rock or slag fragment
Uncertain; possibly limonite/goethite-rich material (FeO(OH)·nH₂O)
mineral