Identify any rockfrom a photo.

Calcite (likely honey/yellow calcite)

Calcite, CaCO₃; a carbonate mineral rather than a rock

Yellow chalcedony (likely lemon agate or yellow jasper)

Microcrystalline quartz, SiO₂; possibly iron-bearing jasper or chrysoprase-like chalcedony

Slate

Slate; fine-grained foliated metamorphic rock, chiefly quartz, muscovite/illite, and chlorite

Porous limestone (likely reef or shell limestone)

Calcium-carbonate rock, predominantly calcite (CaCO₃); possibly bioclastic limestone or coquina

Tumbled green aventurine (probable)

Quartzite dominated by quartz (SiO₂), with green fuchsite mica or chlorite inclusions

Polished turquoise-matrix cabochon

Turquoise, hydrated copper–aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O, with iron-rich matrix and possible chrysocolla

Pink-and-gray rhodonite

Rhodonite, manganese inosilicate (MnSiO₃), commonly with manganese oxides

Polished black gemstone, likely obsidian

Volcanic glass; chiefly silica-rich amorphous SiO₂

Polished carnelian agate

Microcrystalline quartz, SiO₂, commonly chalcedony with iron-oxide coloring

Banded calcite (onyx marble)

Calcite, CaCO₃; commonly sold as Mexican or Pakistani onyx marble

Green cabochon gemstone, likely chrysoprase or dyed chalcedony

Chrysoprase: cryptocrystalline quartz (SiO₂), nickel-colored chalcedony; alternatively dyed chalcedony

Limonite-rich ironstone (probable weathered iron ore)

Hydrated iron oxides, chiefly goethite (FeO(OH)) and limonite (variable FeO(OH)·nH₂O), possibly with hematite