Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Category
Igneous Or Sedimentary
Browse igneous or sedimentary specimens identified by the Rock Identifier community.
Biotite Mica
Biotite, K(Mg,Fe)3AlSi3O10(F,OH)2
mineral
Quartz (vein quartz)
SiO2 (Silicon Dioxide)
Mineral
Quartz (likely Clear Quartz or Rock Crystal)
Quartz (SiO2)
Mineral
River Pebble (Basalt/Greywacke)
Weathered Basalt or Fine-Grained Greywacke
igneous/sedimentary
Pyrite
Pyrite (Iron Disulfide), FeS2
Mineral
Quartz
Silicon dioxide (SiO₂)
Mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Milky Quartz
Quartz (SiO2)
Mineral
Quartz (likely) or a Quartzite Pebble
Silicon dioxide (SiO2) for quartz. If it's quartzite, it's a metamorphic rock primarily composed of quartz.
Mineral, specifically a detrital grain
Mica Group Minerals
There isn't a single scientific name as 'Mica' refers to a group of phyllosilicate minerals. Common scientific names include Muscovite (KAl₂ (AlSi₃O₁₀)(OH)₂), Biotite (K(Mg,Fe)₃AlSi₃O₁₀(OH)₂), Phlogopite (KMg₃AlSi₃O₁₀(OH)₂), and Lepidolite (K(Li,Al)₃(Al,Si,Rb)₄O₁₀(F,OH)₂).
Mineral
River Pebbles and Quartz
Mixed Igneous, Sedimentary, and Metamorphic Rocks (Silicon Dioxide SiO2 dominant)
mixed
Graphite
Graphite (Carbon, C)
Mineral
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
mineral
Orthoclase Feldspar
Orthoclase (KAlSi3O8)
Mineral
Apatite
Apatite Group (e.g., Fluorapatite Ca5(PO4)3F, Chlorapatite Ca5(PO4)3Cl, Hydroxylapatite Ca5(PO4)3(OH))
mineral
Rock Crystal Quartz
Quartz (SiO₂)
Mineral
Nephrite Jade
Nephrite (Ca2(Mg,Fe)5Si8O22(OH)2)
Mineral
Gneiss (specifically a Banded Gneiss pebble)
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Jasper and Basalt Mix (Dark Chert/Basalt River Pebble)
Silicon Dioxide (SiO2) or Mafic extrusive igneous rock
sedimentary or igneous
River Cobble (likely Basalt or Chert)
Siliceous River Rock / Microcrystalline Quartz / Mafic Igneous
igneous/sedimentary
Crystal Quartz Beads (likely Clear Quartz)
Quartz (SiO₂)
Mineral
Fluorite in Matrix
Fluorite (CaF2) within a host rock matrix
Mineral
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Gneiss
Gneiss (Metamorphic rock of variable composition, typically SiO2 rich)
metamorphic
Quartz
Quartz (SiO2 - Silicon Dioxide)
Mineral
Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
mineral
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.
Sedimentary rock
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Muscovite Mica
Muscovite (Potassium Aluminum Silicate Hydroxide Fluoride), KAl2(AlSi3O10)(OH,F)2
mineral
Laterite
Laterite (no specific mineral formula as it's a rock type)
Sedimentary
Quartz (River Pebble)
Quartz (SiO₂ - Silicon Dioxide)
Mineral
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)
Sedimentary
Green Calcite
Calcite (CaCO3)
mineral
Gneiss
Gneiss (High-grade regional metamorphic rock)
metamorphic
Magnetite
Magnetite (Fe3O4)
Mineral
White Topaz
Al2SiO4(F,OH)2
mineral
Calcite
Calcite (CaCO3)
mineral
Quartz
Silicon Dioxide (SiO2)
Mineral
Granite
Granite
igneous
Peridot and Citrine Gemstones (in a ring setting)
Peridot (Olivine: (Mg,Fe)2SiO4), Citrine (Quartz: SiO2)
mineral
Granite
Granite (a plutonic igneous rock composed of quartz, feldspar, and mica)
igneous