Identify any rockfrom a photo.

Rounded river pebble, likely sandstone or weathered quartz-rich sedimentary rock

Indeterminate siliciclastic pebble; likely quartz–feldspar sandstone, with possible iron-oxide staining

Tumbled brown stone, possibly chert or iron-stained quartzite

Indeterminate from photograph; possible microcrystalline quartz (SiO₂)

Rounded yellow-brown river pebble

Indeterminate lithology; possibly weathered sandstone or chert

Rounded yellow sandstone pebble

Quartz-rich sandstone, likely ferruginous or calcareous sandstone

Weathered iron-rich pebble

Likely ferruginous sandstone or ironstone; exact identification requires testing

Weathered iron-rich sandstone or ferruginous quartzite

Quartz-rich sandstone, variably cemented by iron oxides (SiO₂ with hematite/goethite)

Rounded sandstone pebble

Quartz-rich sandstone (primarily SiO₂)

Tumbled yellow jasper

Jasper, microcrystalline quartz (SiO₂), colored mainly by iron oxides

Rounded quartz-rich pebble, possibly chert or weathered sandstone

Indeterminate siliciclastic rock; likely microcrystalline quartz (SiO₂) or quartz-feldspar sandstone

Tumbled yellow-orange calcite

Calcite (calcium carbonate, CaCO₃)

Rounded sandstone pebble

Quartz-rich sandstone (likely arkose or lithic sandstone)

Rounded pink granite pebble

Granite, chiefly quartz, potassium feldspar, plagioclase, and biotite; exact identification is limited by the small image