Biotite (Black Mica)
Biotite - K(Mg,Fe)3AlSi3O10(F,OH)2
mineral
Category
Rock
Browse rock specimens identified by the Rock Identifier community.
Greywacke (River Pebble with Quartz Veins)
Greywacke (Indurated Sandstone); Veins: SiO2 (Quartz)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Basalt with Amygdales
Amygdaloidal Basalt
igneous
Quartz Geode
Silicon Dioxide (SiO2) within a sedimentary or igneous host
sedimentary
Basalt with Quartz Veining
Veined Basalt (composed primarily of plagioclase feldspar, pyroxene, and olivine with quartz/calcite infill)
igneous
Basalt with Quartz/Calcite Veins
Amygdaloidal Basalt (SiO2 or CaCO3 inclusions)
igneous
Quartzite River Pebble
Quartzite (primarily Silicon Dioxide, SiO2)
metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Porphyritic Basalt (Drill Core)
Porphyritic Basalt with Plagioclase Phenocrysts
igneous
Ferruginous Sandstone (Ironstone)
Sandstone with Hematite/Goethite cement (SiO2 + FeO(OH))
sedimentary
Schist
Mica Schist (contains muscovite/biotite and quartz)
metamorphic
Quartz Geode
Crystalline Quartz (SiO2) within a sedimentary/igneous host
mineral
Quartz Geode
Silicon Dioxide (SiO2) in a sedimentary or volcanic host
mineral
Geode (Unopened)
Siliceous Geode (SiO2)
sedimentary
Grey River Pebble (Greywacke / Basalt)
Stream-rounded silicate rock pebble
sedimentary
Fossils in Limestone (Crinoid / Marine Invertebrate Fossil)
Fossiliferous Limestone (containing Crinoidea / Brachiopoda)
fossil
Limestone (Weathered Pebble)
Calcium Carbonate (CaCO3) / Limestone
sedimentary
Quartz-Veined Sandstone
Quartz-veined Arenite
sedimentary
Limestone (River Pebble)
Calcium Carbonate (CaCO3)
sedimentary
Shale
Clastic sedimentary rock (primarily clay and silt minerals)
sedimentary
Clear Quartz (Rock Crystal) Bracelet
Silicon Dioxide (SiO2)
gemstone
Granite Gneiss
Gneiss (High-grade Metamorphic Rock)
metamorphic
Gneiss (Metamorphic Rock)
Gneiss (variable mineral formula primarily containing Quartz, Feldspar, and Mica)
metamorphic
Milky Quartz (Quartz Vein)
Silicon Dioxide (SiO2)
mineral
Not a geological specimen
N/A (man-made object)
N/A
Shale (with Iron Staining)
Argillaceous mudstone / Shale
sedimentary
Quartz Vein in Matrix (Breccia / Host Rock with Quartz)
Silicon Dioxide (SiO2) in Host Rock Matrix
metamorphic
Gneiss
Gneiss
metamorphic
Conglomerate
Conglomerate Rock
sedimentary
Conglomerate
Conglomerate Rock
sedimentary
Porphyry
Porphyritic Rock
igneous
Conglomerate
Conglomerate rock
sedimentary
Quartz (Druzy) in host rock
SiO₂ (Silicon Dioxide) as Quartz, with unspecified host rock components (likely silicates and iron oxides)
Mineral
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) within Metasedimentary or Igneous Matrix
metamorphic
Vesicular Basalt (Scoria)
Vesicular Basalt
igneous
Manhattan Schist
Manhattan Schist (Aluminous Metasedimentary Rock)
metamorphic
Sandstone (with Iron Staining)
Clastic Sedimentary Rock (primarily Quartz with Limonite/Goethite staining)
sedimentary
Unakite
Epidotized Granite
metamorphic
Shale
Shale (Lutite)
sedimentary
Tiger Iron
Tiger Iron (Composition: SiO2, Fe2O3, Fe3O4)
metamorphic
Pink Quartzite
Quartzite (SiO2 with minor iron oxide impurities)
metamorphic