Identify any rockfrom a photo.

Weathered sandstone or iron-stained sedimentary rock

Quartz-rich sandstone, likely ferruginous sandstone

Weathered quartz-rich pebble

Quartz-bearing granitoid or quartzite; exact identification is uncertain from the image

Rounded quartz-rich pebble (likely quartzite)

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

Tumbled basalt pebble

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase and pyroxene, commonly with olivine

Weathered quartz-rich rock, possibly iron-stained quartz or quartzite

Quartz (SiO₂), likely in a quartzite or quartz-vein matrix with iron oxides

Rounded basaltic river pebble

Basalt, predominantly plagioclase and pyroxene, commonly with olivine and iron oxides

Rounded brown granite-like pebble

Likely weathered granite or granodiorite; exact identification requires a fresh surface and testing

Rounded basalt cobble

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase, pyroxene, and commonly olivine

Likely weathered basalt or andesite fragment

Fine-grained volcanic rock, likely basaltic-andesite; exact identification requires testing

Fossiliferous limestone pebble

Bioclastic limestone, chiefly calcite (CaCO₃)

Pink quartz crystal (likely rose quartz)

Quartz, silicon dioxide (SiO₂), possibly rose quartz

Polished/tumbled unakite (probable)

Unakite; epidote + pink potassium feldspar + quartz