Quartz
SiO₂ (Silicon Dioxide)
Mineral
Category
Igneous Or Sedimentary (Anthropogenic Modification)
Browse igneous or sedimentary (anthropogenic modification) specimens identified by the Rock Identifier community.
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Dark basalt or fine-grained mafic rock
Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine or iron-titanium oxides
igneous
Quartz River Pebbles
Silicon Dioxide (SiO2)
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Yellow Jasper
Silicon Dioxide (SiO2)
sedimentary
Basalt and Quartz Pebble
Basalt (Igneous) and Quartzite/Quartz (SiO2) pebble
igneous and sedimentary
Weathered mafic rock, likely basalt
Basalt; primarily plagioclase feldspar, clinopyroxene, and commonly olivine or magnetite
igneous
Banded Agate
Cryptocrystalline Quartz (SiO2)
sedimentary
Blue Moss Agate
Silicon Dioxide (SiO2) with mineral inclusions
sedimentary
Banded Chalcedony (Agate) in Basalt Matrix
Cryptocrystalline Quartz (SiO2) in Mafic Igneous Rock
sedimentary/igneous
Greenschist
Greenschist (composed mainly of chlorite, epidote, actinolite, and albite)
metamorphic
Yellow Quartz Pebble (Citrine or Iron-stained Quartz)
Silicon Dioxide (SiO2)
mineral
Rounded quartz-rich pebble
Likely microcrystalline quartz (SiO₂), possibly milky quartz or a pale quartzite fragment
mineral
Mixed polished river stones
Likely quartz, quartzite, chert/jasper, and possibly limestone or marble
mineral
Calcite
Calcite (calcium carbonate, CaCO₃), likely a massive crystalline specimen
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Almandine Garnet
Almandine, Fe3Al2(SiO4)3
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Gneiss
Gneiss
metamorphic
Banded Gneiss / Metamorphic River Pebble
Gneiss (Foliated Metamorphic Rock)
metamorphic
Gneiss (Gneissic Granite Pebble)
Metamorphic rock rich in Quartz, Feldspar, and Mica
metamorphic
River Pebble (Gneiss / Granitic Schist)
Metamorphic Rock (Quartz-Feldspar-Mica assembly)
metamorphic
White Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Gneiss (Stream-worn Cobble)
Gneiss (Metamorphic rock composed primarily of Quartz, Feldspar, and Mica)
metamorphic
Milky Quartz Vein in Host Rock
Silicon Dioxide (SiO2)
mineral
Green Schist
Greenschist (composed primarily of Chlorite, Actinolite, and Epidote)
metamorphic
Quartz
Silicon Dioxide (SiO2)
mineral
Chalcedony (Agate/Chert)
Silicon Dioxide (SiO₂)
mineral
Quartz (Milky/Cloudy Variety)
Silicon Dioxide (SiO2)
mineral
River Stone (Granitic Gneiss)
Foliated Granitic Gneiss
metamorphic
Pyrite
Iron Disulfide (FeS2)
mineral
Carnelian
Carnelian (Microcrystalline Quartz, SiO2)
Mineral
Yellow Quartz (Citrine Quartz or Yellow Chalcedony)
Silicon Dioxide (SiO2)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Gneiss
Gneiss (High-grade metamorphic rock)
metamorphic
Likely weathered sandstone or quartzite
Quartz-rich sandstone; possibly metamorphosed to quartzite (SiO₂-dominant)
sedimentary
Tiger's Eye (Oeil de Tigre)
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
metamorphic
Clear quartz crystal sphere
Quartz (silicon dioxide, SiO₂)
mineral
Polished blue stone, likely sodalite
Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂; possibly blue-dyed jasper or lapis lazuli
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Gneiss
Banded Metamorphic Rock (Gneiss)
metamorphic