Biotite (Mica)
Biotite (K(Mg,Fe)3AlSi3O10(OH,F)2)
mineral
Category
Igneous, Sedimentary, Or Metamorphic (Mineral Based)
Browse igneous, sedimentary, or metamorphic (mineral based) specimens identified by the Rock Identifier community.
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
mineral
Hag Stone
Perforated Sedimentary Rock
sedimentary
Fossil / Permineralized Bone
Tyrannosaurus rex fossil (Hydroxylapatite replaced by various minerals)
sedimentary
Asphalt Concrete (Bituminous Concrete)
Bituminous aggregate
sedimentary
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Sandstone
Arenite (SiO2 based with mineral cement)
sedimentary
Milky Quartz Pebble
Crystalline Silicon Dioxide (SiO2)
mineral
Sandstone (with biological crust)
Arenite (SiO2 based)
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Sandstone, Quartzite, and River Pebbles
Silicon Dioxide (SiO2) based Sedimentary/Metamorphic structures
Sedimentary and Metamorphic
Yellow Aventurine
Silicon Dioxide with inclusions (SiO2 + Muscovite/Fuchsite)
mineral
Marble
Metamorphosed Limestone (principally CaCO3)
metamorphic
Gneiss
Gneiss
metamorphic
Epidote
Epidote (formula: Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))
mineral
Mica
Phlogopite or Biotite group (KMg3(AlSi3O10)(F,OH)2 / K(Mg,Fe)3AlSi3O10(OH)2)
mineral
Greenschist
Greenschist (Actinolite-Chlorite Schist)
metamorphic
Zoisite with Ruby (Anyolite)
Zoisite – Ca2Al3(SiO4)3(OH) with inclusions of Ruby (Al2O3:Cr)
metamorphic
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Muscovite Mica
Muscovite (Potassium Aluminum Silicate) - KAl2(AlSi3O10)(F,OH)2
mineral
Green Fluorite
Calcium Fluoride (CaF2)
mineral
Shale (with Iron Oxide staining)
Fissile Mudstone (primarily Quartz and Clay minerals)
sedimentary
Anthracite Coal
Anthracite (Carbon-based organic sedimentary rock transitioned to metamorphic)
metamorphic
Muscovite Mica
Muscovite / KAl2(AlSi3O10)(OH)2
mineral
Biotite on Matrix
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
mineral
Mica Schist
Schist (Muscovite/Biotite Schist)
metamorphic
Blue Calcite
Calcium Carbonate (CaCO3)
mineral
Citrine
Silicon dioxide (SiO2)
mineral
Milky Quartz
Quartz (Silicon Dioxide - SiO2)
mineral
Sandstone (with potential trace fossils)
Clastic sedimentary rock (primarily SiO2)
sedimentary
Rhodonite Tumbled Chips
Manganese silicate (Mn,Fe,Mg,Ca)SiO3
mineral
Citrine
Crystalline Quartz (SiO2) with iron impurities
mineral
Fossilized Crab Carapace (Concretion)
Decapoda (fossil), typically preserved in calcite or siderite concretion
sedimentary
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Biotite (Mica)
K(Mg,Fe)3AlSi3O10(OH,F)2
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Gold
Native Gold (Au)
mineral
Peacock Ore
Bornite (Cu5FeS4) or iridescent Chalcopyrite (CuFeS2)
mineral
Sandstone with Secondary Mineral Encrustation
Arenite with Silica/Calcite deposits (SiO2 or CaCO3)
sedimentary
Quartz with Muscovite Mica
Silicon Dioxide (SiO2) with Potassium Aluminum Silicate Hydroxide Fluoride (KAl2(AlSi3O10)(F,OH)2)
mineral
Mixed Chalcedony and Jasper Bracelet (possibly 'Ocean Jasper' or similar banded variety for brown beads, and blue/grey Chalcedony for the translucent beads)
Chalcedony (SiO2), Jasper (SiO2 with impurities)
Mineral (specifically a cryptocrystalline variety of Quartz)
Blue Aventurine
Silicon Dioxide (SiO2) with inclusions of Dumortierite
Mineral (silicate variety)