Quartz Boulder
Silicon Dioxide (SiO2)
mineral
Category
Sedimentary Or Igneous (Secondary Formation)
Browse sedimentary or igneous (secondary formation) specimens identified by the Rock Identifier community.
Learn about Sedimentary Or Igneous (Secondary Formation) in the encyclopedia
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Asphalt Concrete (Bituminous Conglomerate)
Anthropogenic Bituminous Conglomerate
sedimentary
Sandstone (Ferruginous)
Arenite (primarily SiO2 with Fe2O3 inclusions)
sedimentary
Specular Hematite
Hematite (Fe2O3)
mineral
Banded metamorphic river cobble, likely gneiss or metasedimentary rock
Quartz–feldspar–mica gneiss or quartzite with cross-cutting quartz veins
metamorphic
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Dark tumbled stone, likely basalt or black chert
Probable basalt (fine-grained plagioclase–pyroxene rock); chert is an alternative
igneous
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Shale with Vein Infillings
Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.
Sedimentary Rock
Gneiss
Gneiss
metamorphic
Magnetite
Magnetite (Fe3O4)
Mineral
Conglomeratic breccia (possibly polymictic volcanic breccia)
Polymictic breccia; clasts in a fine-grained volcanic or sedimentary matrix
igneous
Milky Quartz with Iron Inclusions
Silicon Dioxide (SiO2)
mineral
Quartz (Citrine or Iron-Stained)
Silicon Dioxide (SiO2)
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Greenstone Pebble
Metabasalt / Greenschist
metamorphic
Vesicular Basalt (Amygdaloidal Basalt)
Basalt with Secondary Mineral Inclusions
igneous
Amygdaloidal Basalt
Basalt with secondary mineral infilling
igneous
Amygdaloidal Basalt
Basalt with Secondary Mineral Infillings
igneous
Amygdaloidal Basalt
Basalt with secondary mineral infilling
igneous
Magnetite-rich ironstone
Magnetite, Fe₃O₄, likely in a dense ironstone matrix
mineral
Calcite
Calcium Carbonate (CaCO3)
mineral
Optical Calcite (Iceland Spar)
Calcium Carbonate (CaCO3)
mineral
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Magnetite
Iron(II,III) oxide (Fe3O4)
mineral
Quartz (Druzy/Macro-crystalline)
Silicon Dioxide (SiO2)
mineral
Hematite with Magnetite
Iron Oxide (Fe2O3)
mineral
Quartz (Agate/Chalcedony variety)
Silicon Dioxide (SiO2)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Quartz / Common Agate
Silicon Dioxide (SiO2)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Quartz–mica metamorphic rock, likely schist
Quartz–muscovite/biotite schist; predominantly SiO₂ quartz with phyllosilicate micas
metamorphic
Quartzite with Druzy Quartz
Silicon Dioxide (SiO2)
metamorphic
Weathered vesicular volcanic rock
Likely basaltic andesite or scoriaceous basalt; exact identification requires fresh surface and testing
igneous
Granite / Igneous Rock Specimen
Phaneritic Igneous Rock
igneous
Raw Quartz
Silicon Dioxide (SiO2)
mineral
Polished magnetite-rich rock, likely magnetite-bearing schist or ironstone
Magnetite (Fe₃O₄) in a foliated silicate matrix; exact identification requires testing
metamorphic
Quartz vein in weathered host rock
Quartz (SiO₂), likely in a weathered metamorphic or igneous matrix
mineral
Black Tourmaline (Schorl)
Schorl (Na(Fe^2+)3Al6(Si6O18)(BO3)3(OH)4)
Mineral
Amygdaloidal Basalt
Extrusive Igneous Rock with Secondary Mineral Fillings
igneous