Identify any rockfrom a photo.

Banded metamorphic rock, likely gneiss

Foliated quartz–feldspar rock (gneiss; exact identification requires closer examination)

Weathered quartz-rich rock, possibly quartzite

Quartzite (tentative identification; exact rock type cannot be confirmed from the image)

Fossilized coral (possible)

Indeterminate fossil; the image does not show enough diagnostic detail to identify a taxon

Milky quartz

Quartz, silicon dioxide (SiO₂)

Greenstone pebble

Likely chlorite- and/or actinolite-bearing metamorphic rock; exact composition cannot be determined from the image.

Rounded pebble, likely quartz-rich river or beach pebble

Unidentified lithic clast; possibly quartzite or iron-stained quartz-rich rock

Quartz-rich pebble

Mostly quartz (SiO₂), possibly a quartzite or vein-quartz fragment

Banded gneiss

Foliated gneiss, likely quartz–feldspar–mica gneiss

Serpentinite pebble

Serpentinite, composed mainly of serpentine-group minerals (commonly antigorite, lizardite, or chrysotile)

Polished fossiliferous agate (likely fossil coral or shell in silica)

Silicified fossil in chalcedony, a microcrystalline form of quartz (SiO₂); exact fossil type is uncertain from the image

Polished banded agate

Agate, a banded variety of microcrystalline quartz (SiO₂)

Weathered granite pebble

Granite, a coarse-grained felsic intrusive igneous rock