Mineral, Specifically A Rock Fragment

Chert (specifically Chalcedony/Flint variant)

Silicon Dioxide (SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Sandstone (lithic/greywacke variant)

Clastic sedimentary rock (primarily SiO2 with rock fragments)

Ironstone Concretion

Ferruginous Sandstone / Siderite Concretion

Granite (specifically Pink or Alkali Feldspar Granite)

Felsic Plutonic Rock (primarily SiO2 with KAlSi3O8)

Serpentine

(Mg,Fe)3Si2O5(OH)4

Pink granite

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

Weathered quartz-rich rock fragment

Likely quartz–feldspar-rich granitoid, possibly granite or granitic gneiss; exact identification is uncertain from the image

Likely galena-bearing rock

Galena (PbS), possibly in a dark host rock

Milky quartz

Quartz (silicon dioxide, SiO₂)

Possible weathered metal-rich rock or slag fragment

Uncertain; possibly iron-oxide-rich breccia or industrial slag

Unidentified rough mineral fragments

Likely quartz- or feldspar-bearing rock; exact identification requires testing

Sandstone (with concrete/human-made layer)

Clastic Sedimentary Rock (primarily Quartz/Feldspar grains)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Granite

Phaneritic Igneous Rock (composed of Quartz, Feldspar, and Mica)

Quartz Crystal Fragment

Silicon Dioxide (SiO2)

Sandstone

Sedimentary Rock (Quartz arenite)

Brecciated Jasper (or Polished Sedimentary Breccia)

Breccia / Microcrystalline Quartz (SiO2)

Waterworn Pebble / Quartzite

Metamorphic/Sedimentary rock fragment

Milky quartz fragment

Quartz (silicon dioxide, SiO₂)

Conical fossil shell or shell fragment

Likely a gastropod shell fragment; exact taxon indeterminate from the image

Iron-stained quartz-rich rock

Quartz (SiO₂), likely with iron-oxide staining; exact rock type is uncertain from the image

Pegmatitic granite fragment

Granitic pegmatite, chiefly quartz, feldspar, and mica

Limestone (specifically Dolomitic/Crystalline Limestone)

Sedimentary Carbonate Rock (CaCO3 / CaMg(CO3)2)

Red Sandstone

Sandstone (principally Quartz with Iron Oxide coating)

Small gray rock fragment

Indeterminate; possibly quartz-rich granite, chert, or concrete-like silicate material

Sandstone

Sandstone (composed predominantly of Quartz, SiO2)

Granite Gravel (Pebble)

Intrusive Felsic Igneous Rock

Sandstone

Sedimentary Rock (Quartzose Sandstone)

Conglomerate

Conglomerate (Sedimentary Clastic Rock)

Granite (likely)

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

Brown Sandstone (River Rock)

Arenite

Weathered sedimentary rock, possibly sandstone

Indeterminate clastic sediment; probable quartz-rich sandstone

Amethyst geode fragment

Quartz, SiO₂, colored by trace iron; purple quartz crystals lining a geode cavity

Sandstone

Sedimentary rock composed mainly of sand-sized minerals or rock grains

Gravel / Limestone Fragment

Calcium Carbonate (CaCO3) / Fine-grained Sedimentary Rock

Weathered quartz-rich rock fragment

Likely quartz-bearing sandstone or granitic rock; exact identification is uncertain from the image

Sandstone Pebble

Sandstone (Silicon dioxide-rich clastic sedimentary rock)

Druzy Quartz (part of a Geode)

Silicon Dioxide (SiO2)

Sandstone

Clastic Sedimentary Rock

Sandstone

Sedimentary Clastic Rock

Rounded gray pebble, likely fine-grained metamorphic rock

Possibly quartz-rich gneiss or granofels; exact identification requires closer examination