Identify any rockfrom a photo.

Yellow chalcedony (possibly jasper/chalcedony)

Microcrystalline quartz, SiO₂; yellow coloration likely from iron oxides/hydroxides

Gneiss

Banded quartz–feldspar–mica gneiss

Likely weathered quartz-rich rock fragment

Uncertain; possibly quartz sandstone or a pale feldspathic rock

Gneiss (possibly migmatitic or strongly folded banded gneiss)

Banded quartz–feldspar–mica gneiss; variable composition, commonly quartz + plagioclase/alkali feldspar + biotite/muscovite ± amphibole

Quartz-rich metamorphic rock, likely milky quartzite

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

Banded gneiss

Quartzo-feldspathic gneiss, likely biotite-bearing

Milky quartz pebble

Quartz, silicon dioxide (SiO₂)

Tumbled serpentinite (likely antigorite-rich)

Serpentinite; chiefly serpentine-group minerals, commonly antigorite, Mg₃Si₂O₅(OH)₄, with magnetite and minor carbonates

Weathered quartz-rich rock, likely quartzite

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

Fossilized wood (petrified wood)

Silicified permineralized wood, commonly quartz (SiO₂) replacing or infilling woody tissue

Fossiliferous wood / petrified wood fragment

Silicified or partially mineralized wood (fossil wood; commonly quartz/chalcedony replacement)

Likely tumbled or polished jasper/chalcedony

Microcrystalline quartz, SiO₂; possibly opaque jasper or pale chalcedony