Metamorphic Rock (Specifically A Rock Composed Of Minerals)

Sandstone (Ferruginous)

Arenite (SiO2 with Fe2O3 inclusions)

Gneiss (Metamorphosed Granitic Rock)

Gneiss (composed mainly of quartz, feldspar, biotite, and/or hornblende)

Quartz-bearing granite or pegmatitic rock

Granite, composed mainly of quartz, feldspar, and mica; exact identification is uncertain from the image

Schist

Schist

Gabbro

Phaneritic Basic Igneous Rock

Chert (White-Tan variety)

Silicon dioxide (SiO2) / Microcrystalline Quartz

Mica Schist

Mica Schist (predominantly composed of Muscovite or Biotite silicates)

Quartz Crystal (specifically Rock Crystal)

Silicon Dioxide (SiO2)

Phyllite (possibly low-grade greenish slate)

Foliated metamorphic rock composed mainly of very fine-grained quartz, mica, and chlorite; approximate composition varies and has no single fixed chemical formula

Sandstone (Quartzose Sandstone)

Sandstone (SiO2 with various trace minerals)

Coarse-grained granite (likely biotite granite)

Granite, composed mainly of quartz and feldspar with dark biotite or amphibole

Pink Granite

Phaneritic Felsic Intrusive Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)

Micaceous Rock (likely Muscovite Schist/Gneiss or a Muscovite-rich Specimen)

Predominantly Muscovite (KAl2(AlSi3O10)(F,OH)2), often found in rocks like Muscovite Schist or Muscovite Gneiss.

Quartzite

Quartzite (SiO2)

Amygdaloidal Basalt

Amygdaloidal Basalt

Pink granite pebble

Granite, composed chiefly of quartz, potassium feldspar, and mica

Montana Moss Agate

Chalcedony (Silicon Dioxide, SiO2)

Greenstone

Protolith: Basaltic rock

Quartzite

Metamorphic rock primarily composed of Quartz (SiO2)

Quartzite Pebble

Metamorphic rock predominantly composed of Quartz (SiO2)

Quartzite Pebble

Metamorphic rock primarily composed of Quartz (SiO2)

Quartzite

Quartzite (Metamorphic rock primarily composed of SiO2)

Quartzite

Metamorphic rock composed primarily of quartz (SiO2)

Quartzite

Metamorphic rock primarily composed of Quartz (SiO2)

Quartzite

Metamorphic rock predominantly composed of Quartz (SiO2)

Quartzite Pebble

Metamorphic rock predominantly composed of Quartz (SiO2)

Quartzite

Metamorphic rock primarily composed of Quartz (SiO2)

Granite

Granite

Montana Moss Agate

Chalcedony (SiO2) with Manganese/Iron oxide inclusions

Sandstone (Micaceous)

Arenite (composed primarily of SiO2)

Weathered granite or granitic rock fragment

Granite; chiefly quartz, feldspar, and mica/amphibole

Fossilized bone fragment

Fossil bone, composed chiefly of carbonate-fluorapatite (bioapatite)

Pale greenish quartz-bearing rock, possibly serpentine or altered feldspar

Tentatively serpentinite-related rock (serpentine-group minerals) or altered granitic material; identification is uncertain from the photograph

White Topaz

Aluminum Silicate Fluoride Hydroxide; Al2SiO4(F,OH)2

Sandstone (Quartz Sandstone / Iron-stained Sandstone)

Sandstone (SiO2 with iron oxide impurities)

Dark gray metamorphic cobble, likely slate or phyllite

Foliated metapelite; possibly slate/phyllite composed mainly of quartz, mica, and chlorite

Pink Granite

Phaneritic Plutonic Rock (Felsic)

Concrete

Anthropogenic Sedimentary Rock (Hydrated Calcium Silicate)

Dark, coarse-grained rock (likely gabbro)

Gabbro, a mafic intrusive igneous rock

Gneiss (rounded cobble)

Quartz–feldspar–mica gneiss; exact mineral proportions cannot be determined from the image

Serpentine Sphere

Serpentinite

Bauxite

Bauxite (Al2O3·2H2O)