Mineral, Part Of A Rock

Gneiss

Metamorphic Gneiss

Chert (Arrowhead Fragment)

Microcrystalline Quartz (SiO2)

Biotite (Mica)

K(Mg,Fe)3AlSi3O10(OH,F)2

Pink Granite

Phaneritic Felsic Igneous Rock (high K-feldspar)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Granite with a polished dark-red granite cobble

Granite; predominantly quartz, feldspar, and mica

Granite (Phaneritic Igneous Rock)

Granite

Polished granite pebble

Granite, a coarse-grained felsic intrusive igneous rock, typically composed of quartz, potassium feldspar, plagioclase, and biotite or other dark minerals

Gold-bearing Quartz and Pyrite

Auriferous Quartz (SiO2 + Au) with Pyrite (FeS2)

Iron-rich quartz rock, possibly hematite/goethite-bearing quartz

Quartz (SiO₂) with iron oxides/hydroxides, chiefly hematite (Fe₂O₃) and goethite (FeO(OH))

Granite

Phaneritic Felsic Igneous Rock (Granite)

Weathered granite or granitic pebble

Granite; primarily quartz, alkali feldspar, plagioclase, and mica

Malachite-Bearing Copper Ore

Cu2CO3(OH)2 (Malachite) in host rock

Granite

Granite (Felsic Plutonic Rock)

Granite

Granite (Phaneritic Igneous Rock)

Weathered dark igneous rock fragment

Likely basalt or andesite; exact identification is uncertain from the photograph

Small quartz-rich rock fragment

Likely quartz-bearing granite, pegmatite, or quartzite; exact identification is uncertain from the photograph

Quartzite River Rock

Quartzite (SiO2)

Rounded quartz-rich pebble

Likely granitoid-derived quartz–feldspar rock; exact identification uncertain from image

Granite

Granite (Felsic intrusive igneous rock)

Quartz Pebble

Silicon Dioxide (SiO2)

Dark weathered river pebble, likely basalt

Basalt; fine-grained mafic rock dominated by plagioclase and pyroxene, commonly with minor olivine and iron oxides

Small gray rock fragment, likely granite or diorite

Uncertain; probable coarse-grained silicate rock dominated by feldspar and quartz, possibly biotite/hornblende

Diorite (River Cobble)

Phaneritic Intermediate Igneous Rock

Granite Pebble (River Rock)

Phaneritic Felsic Igneous Rock

Quartz pebble (Quartztite fragment)

Silicon Dioxide (SiO2)

Quartz-rich breccia or vein quartz with iron staining

Microcrystalline to crystalline SiO₂, likely quartz with iron oxides/hydroxides and altered host rock

Tumbled basalt (likely weathered mafic river pebble)

Basalt; predominantly plagioclase and pyroxene, commonly with olivine and iron oxides

Granite

Granite (Felsic Plutonic Rock)

Chondrite Meteorite

Ordinary Chondrite (L or H Type)

Weathered granite or granitic pegmatite fragment

Granite; chiefly quartz (SiO₂), feldspar, and minor biotite/hornblende

Red Sandstone (Siltstone pebble)

Arenite / Siltstone (Silicon dioxide based with hematite impurities)

Hypersthene

Hypersthene ((Mg,Fe)SiO₃)

Pearl necklace

Pearl: biogenic calcium carbonate, primarily aragonite (CaCO₃), in a conchiolin matrix

Likely silver-gray granite or granitic gneiss fragment

Granite; primarily quartz (SiO₂), feldspar, and mica (exact identification uncertain from image)

Dyed and polished agate pebble

Microcrystalline quartz (SiO₂), likely chalcedony/agate with blue dye

Quartzite pebble

Quartzite, composed predominantly of quartz (SiO₂)

Unidentifiable Rock Fragment

Biotite Schist

Biotite-rich Schist

Painted River Rock

Polished fluvial clast with acrylic/synthetic pigment coating

Granite

Granite (Phaneritic intrusive igneous rock)

Small brown rock fragment; exact identification uncertain

Unidentified fine-grained lithic fragment