Muscovite Mica
Muscovite (Potassium Aluminum Silicate) - KAl2(AlSi3O10)(F,OH)2
mineral
Category
Metamorphic And Igneous
Browse metamorphic and igneous specimens identified by the Rock Identifier community.
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Silicified oyster fossil
Fossil oyster shell, commonly Ostrea or Crassostrea, replaced or encrusted by chalcedony/quartz
fossil
Milky quartz pebble
Quartz (silicon dioxide, SiO₂)
mineral
Magnetite Sand (Black Sand)
Magnetite (Fe3O4)
mineral
Weathered schist or gneiss fragment
Quartz–feldspar–mica metamorphic rock; likely mica schist or gneiss
metamorphic
Small quartz-rich pebble or rock fragment
Quartz (silicon dioxide, SiO₂), possibly with iron-oxide staining or host-rock inclusions
mineral
Muscovite mica
Muscovite, KAl₂(AlSi₃O₁₀)(OH)₂
mineral
Black Tourmaline
Schorl (Na(Fe²⁺)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)
Mineral
Osumilite in Granite Matrix
(K,Na)(Fe,Mg)2(Al,Fe)3(Si,Al)12O30
mineral
Plagioclase Feldspar (specifically Albite/Oligoclase)
(Na,Ca)(Si,Al)4O8
mineral
Foliated Gneiss
Gneiss (Metamorphic Rock)
metamorphic
Gneiss
Foliated Metamorphic Gneiss
metamorphic
Gneiss
Gneissic Metamorphic Rock
metamorphic
Magnetite
Magnetite (Fe3O4)
mineral
Weathered granite or granitic gneiss
Granite; mainly quartz (SiO₂), feldspar, and mica; possible weak gneissic texture
igneous
Banded Gneiss
Gneiss (Metamorphic Rock)
metamorphic
Schist
Metamorphic Rock (Schist)
metamorphic
Possible magnetite fragment
Magnetite (Fe₃O₄), tentative identification
mineral
Uncertain gray metamorphic rock, likely gneiss or schist
Quartz–feldspar–mica rock; exact identification requires close examination
metamorphic
Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
mineral
Gneiss
Metamorphic Gneiss
metamorphic
Petrified wood
Silicified wood; commonly quartz/chalcedony (SiO₂) replacing organic tissue
fossil
Polished fossil coral
Fossilized coral, commonly agatized coral (silica replacing CaCO₃)
fossil
Likely weathered fossil shell or fossiliferous limestone
Indeterminate molluscan fossil, possibly a bivalve or brachiopod preserved in carbonate rock
fossil
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Magnetite (Lodestone)
Iron(II,III) oxide (Fe3O4)
mineral
Epidote
Epidote Group (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))
metamorphic
Epidote
Epidote (Ca2(Al2,Fe3+)AlSi3O12(OH))
mineral
Small brown mineral fragment, possibly garnet
Unidentified; garnet is a tentative visual possibility (garnet-group silicates, X₃Y₂(SiO₄)₃)
mineral
Quartz
SiO2 (Silicon Dioxide)
Mineral
Quartz
Silicon dioxide (SiO2)
mineral
Clear quartz crystal
Quartz (SiO₂), likely a small rough or naturally fractured crystal
mineral
Small rounded mineral/rock fragment
Indeterminate; possibly quartz-rich stone or feldspar
mineral
Small tumbled pebble (likely quartz or feldspar)
Indeterminate; probable quartz (SiO₂) or feldspar
mineral
Small rough mineral/rock fragment
Indeterminate; possibly quartz-bearing rock or weathered feldspar
mineral
Quartz and Unakite
SiO2 (Quartz) / Epidote, Pink Orthoclase, Quartz (Unakite)
mineral/igneous
Quartz pebble with iron staining
Silicon dioxide (SiO2) with iron oxide impurities
mineral
Small rounded stone or mineral fragment
Indeterminate; likely a common quartz- or feldspar-bearing silicate fragment
mineral
Magnetite / Iron-Rich Basalt
Magnetite bearing Mafic Rock (Fe3O4)
igneous
Magnetite or Hematite Nodule
Iron Oxide (Fe3O4 or Fe2O3)
mineral
Quartz (Gravel Pebble)
Silicon Dioxide (SiO2)
sedimentary
Moonstone (with Tourmaline/Mica)
Orthoclase/Albite Feldspar (KAlSi3O8 / NaAlSi3O8)
mineral