Identify any rockfrom a photo.

Foliated metamorphic rock, likely gneiss or schist

Biotite–quartz–feldspar gneiss/schist; exact identification requires a fresh surface and testing

Weathered gray sandstone or siltstone

Clastic sedimentary rock, likely quartz–feldspar-rich sandstone/siltstone

Polished rutilated quartz cabochon

Quartz (SiO₂) with rutile inclusions (TiO₂)

Weathered iron-rich rock, possibly banded iron formation

Hematite–goethite-rich ironstone; possible BIF (Fe₂O₃/FeO(OH) with quartz)

Granite

Coarse-grained felsic intrusive igneous rock, chiefly quartz, K-feldspar, plagioclase, and mica (commonly biotite).

Clear quartz crystal (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Rounded quartz-rich pebble

Milky quartz or quartzite; predominantly silicon dioxide (SiO₂)

Clear quartz crystal (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Clear quartz crystal (likely)

Quartz, silicon dioxide (SiO₂)

Rounded beach pebbles, likely quartz-rich sandstone and weathered quartzite

Quartz-rich sandstone (SiO₂-bearing) and possible quartzite; exact identification requires testing

Rose quartz (likely tumbled fragment)

Quartz, silicon dioxide (SiO₂), pink variety

Iron-stained quartzite or quartz-rich rock fragment

Quartzite; predominantly silicon dioxide (SiO₂), with iron-oxide staining