Industrial Byproduct

Bituminous Coal

Bituminous coal (Carbonaceous sedimentary rock)

Peridot ring

Gem-quality olivine, typically forsterite–fayalite solid solution ((Mg,Fe)₂SiO₄)

Smoky quartz crystal fragment

Quartz (silicon dioxide, SiO₂), likely smoky variety

Milky quartz pebble

Quartz, SiO₂ (microcrystalline to crystalline variety)

Red cabochon ring, likely ruby or synthetic ruby

Corundum (Al₂O₃), possibly chromium-bearing ruby; the image cannot establish whether it is natural or synthetic

Green sea glass (likely)

Anthropogenic glass, not a mineral; composition commonly soda–lime silicate glass

Milky quartz

Quartz (silicon dioxide, SiO₂)

Ruby (faceted gemstone in a ring)

Corundum, Al₂O₃; red color typically from trace chromium

Colorless faceted gemstone, likely a small diamond or imitation

Undetermined; diamond is carbon (C), but visual appearance alone cannot distinguish it from cubic zirconia or glass

Waterworn pebble, possibly iron-rich basalt or river stone

Unidentified lithic clast; composition cannot be determined reliably from the image

Tumbled, iron-stained quartz-rich pebble

Likely quartz/chalcedony with iron-oxide staining; exact rock type cannot be determined from the image

Fossilized scallop shell fragment

Bivalve shell, composed primarily of calcite (CaCO₃)

Blue gemstone ring (likely sapphire)

Likely corundum, Al₂O₃; the dark, reflective appearance may also indicate a treated or synthetic stone.

Tumbled brown jasper (likely)

Microcrystalline quartz, SiO₂; jasper is an opaque variety of chalcedony

Clear quartz crystal pendant

Quartz (silicon dioxide, SiO₂)

Clear quartz crystal

Quartz (SiO₂), likely a natural crystal point

Small tan rock fragment

Unidentifiable lithic fragment; mineral composition undetermined

Polished red jasper

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

Amethyst (likely synthetic or treated)

Purple quartz, SiO₂; color caused mainly by trace iron and irradiation

Milky quartz

Quartz (silicon dioxide, SiO₂)

Clear quartz crystal

Quartz (silicon dioxide, SiO₂)

Pyrite (likely)

Pyrite, iron sulfide (FeS₂)

Small weathered rock fragment, possibly quartz-rich

Unidentified lithic fragment; species cannot be determined from the image

Polished orbicular jasper (likely ocean jasper)

Orbicular jasper; chiefly microcrystalline quartz and chalcedony (SiO₂), with assorted mineral inclusions

Fossil shark tooth

Likely fossilized shark tooth, possibly Carcharhinus or a related requiem shark

Tiny amber-colored crystal or mineral fragment

Indeterminate from image; possibly quartz, citrine, topaz, or iron-stained feldspar

Sandstone Pebble

Arenite (Siliclastic sedimentary rock)

Sandstone (Ferruginous)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 cement)

Quartzite Pebble

Metamorphosed Silicon Dioxide (SiO2)

Sandstone

Arenite

Gold-bearing Quartz / Auriferous River Rock

Lode Gold in Quartz Matrix (SiO2 + Au)

Quartzite with Quartz Veining

Metamorphosed Quartz-rich Sandstone (SiO2)

Peridotite (Olivine Rock)

Peridotite (composed largely of olivine, (Mg, Fe)2SiO4)

Garnet (Almandine)

Almandine (Fe3Al2(SiO4)3)

Quartzite Cobble

Quartzite (SiO2)

Red Sandstone

Ferruginous Sandstone (SiO2 dominated with Fe2O3)

Lava Rock (Basaltic Scoria)

Vesicular Basalt

Garnet in Quartzite

Garnet-bearing Quartzite (SiO2 + X3Y2(SiO4)3)

Red Sandstone

Sandstone (lithic arenite or arkose with iron oxide)

Quartzite Pebble

SiO2 (Silicon Dioxide)

Basalt (Weathered)

Mafic Igneous Rock

Cubic Zirconia (Jewelry Setting)

Cubic Zirconia (ZrO2)