Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
Category
Browse mixed (predominantly sedimentary and igneous) specimens identified by the Rock Identifier community.
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
Jade (likely Nephrite or Jadeite)
Nephrite (Ca2(Mg,Fe)5Si8O22(OH)2) or Jadeite (Na(Al,Fe3+)Si2O6)
Orthoclase Feldspar
Orthoclase (KAlSi3O8)
Apatite
Apatite Group (e.g., Fluorapatite Ca5(PO4)3F, Chlorapatite Ca5(PO4)3Cl, Hydroxylapatite Ca5(PO4)3(OH))
Rock Crystal Quartz
Quartz (SiO₂)
Nephrite Jade
Nephrite (Ca2(Mg,Fe)5Si8O22(OH)2)
Gneiss (specifically a Banded Gneiss pebble)
Gneiss (High-grade Regional Metamorphic Rock)
River Cobble (likely Basalt or Chert)
Siliceous River Rock / Microcrystalline Quartz / Mafic Igneous
Jasper and Basalt Mix (Dark Chert/Basalt River Pebble)
Silicon Dioxide (SiO2) or Mafic extrusive igneous rock
Crystal Quartz Beads (likely Clear Quartz)
Quartz (SiO₂)
Fluorite
Fluorite (Calcium Fluoride, CaF2)
Fluorite in Matrix
Fluorite (CaF2) within a host rock matrix
Gneiss
Gneiss (Metamorphic rock of variable composition, typically SiO2 rich)
Sandstone or Siltstone
Arenite (if sandstone)
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
Quartz
Quartz (SiO2 - Silicon Dioxide)
Pebble (likely a type of sandstone or quartzite pebble)
Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.
Laterite
Laterite (no specific mineral formula as it's a rock type)
Muscovite Mica
Muscovite (Potassium Aluminum Silicate Hydroxide Fluoride), KAl2(AlSi3O10)(OH,F)2
Obsidian and Green Calcite
Volcanic Glass and Calcium Carbonate (CaCO3)
Quartz (River Pebble)
Quartz (SiO₂ - Silicon Dioxide)
Sandstone (Pebble/Cobble)
Sandstone (arenite is a more precise term for sandstone with less than 15% matrix; this specimen appears to be a lithic or quartz arenite)
Green Calcite
Calcite (CaCO3)
Gneiss
Gneiss (High-grade regional metamorphic rock)
Magnetite
Magnetite (Fe3O4)
White Topaz
Al2SiO4(F,OH)2
Calcite
Calcite (CaCO3)
Quartz
Silicon Dioxide (SiO2)
Granite
Granite
Peridot and Citrine Gemstones (in a ring setting)
Peridot (Olivine: (Mg,Fe)2SiO4), Citrine (Quartz: SiO2)
Granite
Granite (a plutonic igneous rock composed of quartz, feldspar, and mica)
Quartz (likely milky/gray variety)
Quartz (SiO₂)
Chalcedony (Banded/Mottled Variety)
Chalcedony (a cryptocrystalline variety of Quartz, SiO2)
Muscovite Mica
Muscovite (KAl₂(AlSi₃O₁₀)(F,OH)₂))
Schist
N/A (a rock type, not a mineral formula)
Dark-colored Igneous Rock (likely Basalt or Diabase)
Basalt (extrusive igneous) or Diabase (intrusive igneous)
Clear Quartz (Rock Crystal)
Quartz (SiO₂)
Quartz
Silicon Dioxide (SiO2)
Pumice
Pumice (volcanic rock)
Jasper in Basalt Matrix
Silicon Dioxide (SiO2) with impurities; Chalcedony
Quartz (Rock Crystal)
Quartz (SiO₂ - Silicon Dioxide)
Quartz
Quartz (SiO₂)