Metamorphic (Man Made)

Gneiss

Foliated quartz–feldspar–mica gneiss

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (silicon dioxide, SiO₂); if granular and foliated, likely quartzite

Magnetite-rich iron ore (probable magnetite schist)

Magnetite (Fe₃O₄) in a foliated metamorphic matrix, possibly magnetite–biotite schist

Milky quartz

Quartz (silicon dioxide, SiO₂)

Quartz Mineral

Silicon Dioxide (SiO2)

Likely polished garnet fragment

Garnet group, possibly almandine (Fe₃Al₂Si₃O₁₂)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Hornblende-bearing metamorphic rock (probable amphibolite)

Amphibolite; chiefly hornblende amphibole and plagioclase feldspar

Milky quartz (likely)

Quartz, silicon dioxide (SiO₂)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Mixed Quartz and River Pebbles (Stone Collection)

Mixed assortment containing mainly Silicon Dioxide (SiO2)

Quartz-rich sandstone or quartzite

Quartzite; predominantly crystalline SiO₂, possibly with feldspar and iron-oxide staining

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Red garnet-like faceted pendant

Possibly almandine garnet, Fe₃Al₂(SiO₄)₃; identification is uncertain from the image

Citrine Quartz

Silicon Dioxide (SiO2) with ferric iron impurities

Milky quartz (rough quartz specimen)

Quartz, silicon dioxide (SiO₂)

Iron-rich quartzite or ferruginous metamorphic rock

Quartzite, predominantly SiO₂, stained by iron oxides (hematite/goethite)

Serpentine (likely serpentinite)

Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; commonly Mg₃Si₂O₅(OH)₄

Weathered quartz-rich rock, likely milky quartz with iron staining

Quartz (SiO₂), possibly quartz vein material or quartzite

Tumbled milky quartz

Quartz (SiO₂), likely translucent white variety

White quartz bead strand

Quartz, silicon dioxide (SiO₂), likely milky or translucent quartz; beads are polished and drilled

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Road-surface aggregate (crushed stone)

Unidentifiable mixed lithic aggregate; likely basaltic/andesitic fragments with feldspar, quartz, and weathered rock

Likely garnet-bearing rock fragment

Garnet-bearing schist or gneiss; garnet is commonly almandine, Fe₃Al₂(SiO₄)₃

Pink Quartzite

Quartzite (principally Silicon Dioxide, SiO2)

Banded gneiss pebble

Gneiss, commonly quartz–feldspar–mica gneiss

Likely amphibolite

Amphibolite, composed mainly of hornblende and plagioclase feldspar

Likely tumbled quartz or feldspar fragment

Quartz (SiO₂) or feldspar-group silicate

Anthracite coal

Anthracite; predominantly carbon (C), with minor mineral impurities

Quartzite (River Cobble)

Quartzite (predominantly SiO2)

Iron-rich quartzite or ironstone fragment

Quartzite dominated by quartz (SiO₂), with iron oxides such as hematite/goethite

Quartz

SiO₂ (Silicon Dioxide)

Quartz-bearing sandstone or quartzite fragment

Likely quartzite with iron-oxide staining; exact identification is uncertain from the photograph

Rounded quartz-rich pebble

Quartzite (probable), composed predominantly of quartz (SiO₂)

Granite

Granite (felsic intrusive igneous rock)

Likely quartz cabochon in a ring

Quartz (SiO₂), possibly clear or milky quartz; identification is uncertain from the photograph

Quartz

Silicon Dioxide (SiO2)

Native Gold (in Jewelry)

Gold (Au)

Quartz-rich metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica metamorphic aggregate; exact identification requires thin-section or field tests

Quartz-rich metamorphic rock (likely quartzite)

Quartzite; predominantly microcrystalline quartz (SiO₂), with probable iron-oxide staining and minor feldspar/mica

Likely quartz-rich metamorphic rock (quartzite)

Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with mica or feldspar

Tumbled ruby in matrix

Corundum (Al₂O₃), commonly with mica, calcite, or other matrix minerals