Identify any rockfrom a photo.

Dark mafic rock, likely altered basalt or gabbro

Fine- to medium-grained mafic silicate rock; probable basaltic composition with plagioclase and pyroxene, possibly chloritized/serpentinized

Dark metamorphic rock, likely schist or phyllite

Quartz–mica schist/phyllite; chiefly quartz, mica, and feldspar

Polished black-and-golden jasper

Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide/goethite impurities

Polished carnelian agate

Microcrystalline quartz (chalcedony), SiO₂, colored mainly by iron oxides

Polished honey/brown agate (likely carnelian chalcedony)

Microcrystalline quartz, SiO₂; chalcedony with iron-oxide coloration

Calcite-rich limestone or marble fragment

Calcite (CaCO₃), likely recrystallized carbonate rock

Polished black metamorphic stone, likely serpentinite or amphibolite

Serpentinite (mainly serpentine-group minerals) or amphibolite (hornblende–plagioclase); exact identification requires testing

Polished yellow jasper

Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities

Honey-colored chert or flint fragment

Microcrystalline quartz (SiO₂), likely chalcedony-rich chert

Fossilized bone fragment (probable mammalian tooth or bone)

Mineralized bone, commonly hydroxyapatite [Ca5(PO4)3(OH)] replaced or impregnated by silica/calcite

Polished stromatolite (likely fossilized microbial mat)

Fossil stromatolite; chiefly microcrystalline quartz (SiO₂), commonly replacing carbonate

Fossilized tooth, likely mammalian molar

Silicified or mineral-replaced mammalian tooth; exact taxon cannot be determined from the image