Identify any rockfrom a photo.

Tumbled chalcedony (likely carnelian/agate)

Microcrystalline quartz, SiO₂; chalcedony, with possible iron-oxide coloring

Likely small metallic meteorite fragments

Unclassified iron or stony-iron meteorite; mineralogy cannot be confirmed from the image

Unidentified weathered rock fragments

Likely mixed silicate rocks; specific identification requires testing

Polished amethyst pyramid

Amethyst, purple quartz (SiO₂)

Banded calcite marble

Calcite-rich marble (CaCO₃), likely impure marble

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Biotite-bearing granite or granodiorite

Coarse-grained quartz–feldspar rock with biotite; approximate composition: quartz + plagioclase/K-feldspar + biotite ± hornblende

Granite (likely biotite granite)

Coarse-grained granitic rock; chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende

Polished dark stone, likely basalt

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

Weathered granitic rock, likely granodiorite

Granodiorite: quartz, plagioclase feldspar, potassium feldspar, and biotite/hornblende

Tumbled pegmatitic granite

Granite, chiefly quartz–feldspar–mica; likely altered pegmatite

Pegmatitic granite

Coarse-grained granite, chiefly quartz, feldspar, and mica; likely a granitic pegmatite