Mineral, Possibly Rock Fragment Containing A Mineral

Quartz-rich pegmatite (possibly tourmaline-bearing)

Granitic pegmatite; chiefly quartz (SiO₂), feldspar, and dark mica/amphibole

Weathered granite

Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica

Small brown mineral or rock fragment

Undetermined; the image does not show enough detail for reliable identification

Quartz-bearing granite or pegmatitic rock

Granite, composed mainly of quartz, feldspar, and mica; exact identification is uncertain from the image

Polished dark stone fragment, possibly slate or schist

Fine-grained foliated metamorphic rock; exact mineral composition is indeterminate from the image

Iron-rich weathered rock, possibly limonite/goethite-bearing laterite

Limonite (amorphous hydrated iron oxides), commonly mixed with goethite (α-FeO(OH)) and hematite

Dark gray stone, possibly basalt or andesite

Fine-grained mafic to intermediate volcanic rock; precise identification is limited by the cropped image

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Conglomerate (possibly concrete-like natural breccia)

Lithified, poorly sorted clastic rock with angular to subrounded mineral and rock fragments in a finer matrix

Mixed mineral and rock specimen collection

Assorted silicates, carbonates, oxides, and sulfides; individual species cannot be reliably identified from this image

Vesicular basalt with secondary crystals

Basalt, likely zeolite- or calcite-lined vesicular basalt

Quartz-rich pebble

Mostly quartz (SiO₂), possibly a quartzite or vein-quartz fragment

Unidentified rock fragments

Indeterminate; likely a weathered, iron-stained silicate rock

Red Tuff / Sandstone

Rhyolitic Tuff / Pyroclastic Volcanic Rock

Yellow-brown stone or mineral fragment

Unidentified; the image does not show enough detail for a reliable identification

Granite Pebble

Intrusive Igneous Rock

Small fossilized tooth, possibly a shark tooth

Indeterminate fossil tooth; species cannot be identified from this image

Sandstone

Sandstone (clastic sedimentary rock)

Light-colored limestone (probable fossiliferous or micritic limestone)

Calcite-rich carbonate rock; predominantly CaCO₃ (calcite)

Generic Pebble

Lithic Fragment

Sandstone (with vugs or solution cavities)

Arenite (primarily Quartz and Feldspar with CaCO3 or SiO2 cement)

Mixed tumbled gemstone and mineral lot

Primarily quartz varieties (SiO₂), feldspar, beryl/chalcedony, and other unidentified silicate minerals

Pale greenish stone, likely serpentine or altered ultramafic rock

Serpentinite (主要 minerals: antigorite/lizardite, Mg3Si2O5(OH)4); identification is tentative from the image

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Felsic Tuff

Pyroclastic volcanic rock (Tuff)

Small reddish-brown mineral fragment

Uncertain; possibly iron-stained quartz, feldspar, or garnet

Dark veined metamorphic rock, likely serpentinite

Serpentinite; predominantly serpentine-group minerals, possibly with magnesite or calcite veins

Chert Nodule (Fossiliferous Chert)

Microcrystalline Quartz (SiO2)

Sandstone (likely Arkosic)

Clastic Sedimentary Rock (Sandstone)

Small gray rock fragment, likely granite or diorite

Uncertain; probable coarse-grained silicate rock dominated by feldspar and quartz, possibly biotite/hornblende

Amethyst

Quartz, violet variety — silicon dioxide (SiO₂) colored mainly by iron impurities and irradiation

Quartz-rich rock, possibly pegmatite

Likely quartz–feldspar pegmatite; exact identification is uncertain from the photograph

Granite

Intrusive Igneous Rock

Rock crystal (clear quartz), possibly cloudy quartz

Quartz, silicon dioxide (SiO₂)

Small metallic mineral fragment

Indeterminate; possibly galena, hematite, magnetite, or metallic meteorite fragment

Banded Sandstone

Arenite (Sandstone with iron oxide banding)

Likely quartz-rich rock fragment

Quartz (SiO₂), possibly a fragment of quartzite or silica-rich slag

Likely dark rounded stone or mineral fragment

Indeterminate; possibly a water-worn mafic rock such as basalt

Pale green translucent mineral fragment

Indeterminate; possibly fluorite, calcite, or glassy quartz

Basalt

Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)

Druzy Quartz on Matrix

Silicon Dioxide (SiO2)

Weathered stone, likely sandstone or altered volcanic rock

Indeterminate; possibly quartz-rich sandstone or weathered tuff