Not A Rock Or Mineral (Anthropogenic Material)

Iron-rich sandstone concretion

Ferruginous sandstone, cemented chiefly by iron oxides (such as goethite and hematite)

Quartz pebble

Silicon dioxide (SiO2)

Sandstone

Sedimentary Rock (Quartz Arenite)

Concrete with Aggregate

Composite construction material; primary matrix is Calcium Silicate Hydrate (C-S-H)

Small dark metallic-looking rock fragment

Undetermined; possibly iron oxide-rich material or a metallic mineral

Quartz

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 principal component)

Sandstone (Calcareous/Lithic)

Sedimentary Rock (Clastic Sandstone with Calcium Carbonate cement)

Quartz Geode

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 predominantly)

Sandstone

Arenite

Banded gneiss pebble

Biotite–quartz–feldspar gneiss (composition variable)

Sandstone Pebble

Sedimentary Clastic Rock (Quartz Arenite)

Petrified Wood

Silicified Wood (SiO2)

Sandstone with Mineral Veining or Crust

Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)

Metamorphic rock outcrop, likely schist or gneiss

Foliated metamorphic rock; exact mineral assemblage cannot be determined from the image

Weathered porphyritic volcanic rock (likely basaltic andesite)

Porphyritic basaltic andesite; mineral assemblage likely plagioclase, pyroxene, and iron oxides

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock (primarily SiO2)

Weathered conglomerate

Polymictic clast-supported conglomerate, with a sandy or finer-grained matrix

Fossil gastropod shell

Fossilized marine gastropod; exact genus/species cannot be determined from the image

Sandstone/Quartzite

Sedimentary Rock (composed mainly of SiO2)

Nephrite Jade

Nephrite

Fossil gastropod shell

Fossilized gastropod, likely a small marine snail; exact genus cannot be determined from the image

Sandstone

Sedimentary Clastic Rock (Quartz-rich)

Sedimentary Sandstone (Sandstone Slab)

Arenite (SiO2 with Fe2O3 staining)

Iron-stained quartz-bearing rock

Quartz (SiO₂), likely with limonite/goethite iron oxides and possibly feldspar

Granite Sand (Decomposed Granite)

Grus / Quartz-Feldspar Detritus

Polished orange-and-white stone, likely quartz-rich granite or feldspar-bearing rock

Indeterminate from the image; possibly potassium-feldspar-rich granitoid, composed mainly of quartz and feldspar

Sandstone

Arenite (composed mainly of SiO2)

Sandstone (Quartz-rich)

Arenite (primarily SiO2)

Uncertain fine-grained rock or mineral-bearing specimen

Indeterminate; possible quartz- or feldspar-bearing matrix with reflective grains

Sandstone

Arenite (Sandstone)

Sandstone

Arenite (Sedimentary rock composed of sand-sized grains)

Mixed gemstone bead strand, likely amethyst and assorted colored stones

Likely purple quartz (amethyst, SiO₂) mixed with unidentified green, orange, and reddish beads

Tumbled serpentine with dark magnetite/chromite matrix

Serpentinite; chiefly antigorite/lizardite, Mg3Si2O5(OH)4, with magnetite and possibly chromite

Polished red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Sandstone

Arenite (SiO2 based)

Sandstone (likely Quartz Sandstone)

Arenite (composed primarily of SiO2)

Sandstone (Calcareous)

Clastic sedimentary rock (primarily SiO2 with CaCO3 cement)

Milky Quartz with Chlorite/Amphibite Inclusions

Silicon Dioxide (SiO2) with various mineral inclusions

Sandstone

Arenite (SiO2 based with mineral cements)

Sandstone Pebble

Arenite (Siliclastic sedimentary rock)