Identify any rockfrom a photo.

Chalky limestone

Micritic limestone, chiefly calcite (CaCO₃)

Red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Milky quartz cluster

Quartz (silicon dioxide, SiO₂), massive to drusy crystalline aggregate

Rounded green-gray pebble, likely serpentinite

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite

Tumbled brown jasper

Microcrystalline quartz (SiO₂), commonly with iron-oxide impurities

Tumbled rhodonite

Rhodonite, manganese inosilicate (MnSiO₃)

Veined metamorphic cobble, likely serpentinite

Serpentinite, commonly dominated by antigorite/lizardite with magnetite and cross-cutting quartz or calcite veins

Iron-stained quartzite or silicified breccia

Quartz-rich rock dominated by microcrystalline quartz (SiO₂), with iron oxides/hydroxides such as hematite and goethite

Gray chert or silicified limestone

Microcrystalline quartz (SiO₂), possibly with calcite (CaCO₃)

Rounded sandstone or quartz-rich river cobble

Indeterminate lithic sandstone; chiefly quartz (SiO₂) with feldspar and iron-oxide/calcite cement

Weathered metamorphic rock, likely greenschist or amphibolite

Chlorite–actinolite schist/amphibolite; composition likely quartz, feldspar, chlorite, amphibole, and epidote

Weathered granite or granitic gneiss

Granite; primarily quartz, feldspar, and mica (possibly foliated as gneiss)