Identify any rockfrom a photo.

Small tumbled quartz pebbles

Quartz, SiO₂; likely iron-stained and milky varieties

Milky quartz with iron-oxide staining

Quartz (SiO₂), massive variety; minor hematite/goethite staining

Alluvial stream gravel (mixed rock specimens)

Polymictic fluvial deposit; likely mixtures of quartzite, sandstone, shale, chert, basalt, and granite-derived minerals

Weathered quartz-bearing metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica assemblage; exact mineral identification requires testing

Schist, likely garnet–mica schist

Mica schist dominated by biotite/muscovite, quartz, feldspar, and possible garnet

Tumbled turquoise

Turquoise, hydrated copper aluminum phosphate — CuAl₆(PO₄)₄(OH)₈·4H₂O

Polished Labradorite cabochon

Labradorite, Ca( Na,Ca)(Al,Si)₄O₈; plagioclase feldspar

Weathered granite or granitic gneiss cobble

Quartz–feldspar–mica granitoid; exact identification requires a fresh surface or testing

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly with feldspar and mica impurities

Blue-green serpentinite (likely copper-stained)

Serpentinite; chiefly serpentine-group minerals, commonly with malachite/chrysocolla or other copper minerals

Chrysocolla-bearing rock (likely chrysocolla in a host rock)

Chrysocolla, hydrated copper aluminosilicate: approximately (Cu,Al)₂H₂Si₂O₅(OH)₄·nH₂O

Tumbled greenstone, likely serpentine

Serpentinite; mainly antigorite/lizardite/chrysotile, Mg₃Si₂O₅(OH)₄