Industrial Byproduct (Anthropogenic Rock Like Material)

Quartz-rich polymict conglomerate (possibly hydrothermal breccia)

Clast-supported polymict conglomerate dominated by quartz; includes chalcedony/quartz and dark lithic clasts

Likely ironstone or iron-oxide–stained pebble

Iron-rich concretion, probably goethite/limonite (FeO(OH)·nH₂O) coating a rock fragment

Basalt

Aphanitic Mafic Volcanic Rock (Fe/Mg rich)

Tumbled amber-colored chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

Pegmatite

Pegmatite (felsic intrusive igneous rock)

Clear Quartz / Diamond (untested)

Silicon Dioxide (SiO2) or Carbon (C)

Dalmatian jasper

Quartz-bearing alkali feldspar syenite/porphyritic igneous rock, commonly marketed as Dalmatian jasper

Coquina (Fossiliferous Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Pegmatite or Graphic Granite

Intrusive Igneous Rock

Faceted glass-like gemstone object

Likely synthetic glass or cubic zirconia; exact material cannot be confirmed from the image

Sandstone

Arenite (SiO2 based)

Quartz-rich geode or mineralized cavity in host rock

Likely a quartz-bearing geode; the pale crystals may be quartz (SiO₂), but the photo is not detailed enough for a firm identification.

Small dark metallic-looking rock fragment

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

Rounded river pebble, likely quartz-rich stone

Unidentified lithic clast; exact mineralogy cannot be determined from the image

Petrified Wood

Silicified wood (primarily quartz, SiO2)

Sandstone (Ferruginous)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 cement)

Likely coral fragment or calcareous fossil

Aragonite/calcite (CaCO₃), possibly fossil coral such as Pocillopora or a bryozoan

Basalt

Extrusive Igneous Basalt

Vesicular Basalt

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Pink Sapphire

Corundum (Al2O3)

Amethyst cluster (quartz geode fragment)

Amethyst, purple variety of quartz; silicon dioxide (SiO₂) colored mainly by iron-related defects

Fossilized wood, likely silicified petrified wood

Silicified wood (fossil wood; commonly quartz/chalcedony replacing organic tissue)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Quartzite

Quartzite (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Granitic Pegmatite

Pegmatitic Granite

Sandstone with Concretions / Liesegang Rings

Arenite with iron oxide banding

Tumbled rose quartz (probable)

Quartz, silicon dioxide (SiO₂), rose-colored variety

Limestone

CaCO3 (principally Calcite)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Polished Picasso jasper

Silicified carbonate rock, commonly marketed as Picasso jasper; composition varies and is not a single mineral species

Sandstone

Arenite (primarily SiO2)

Weathered jasper-rich breccia

Silicified iron-rich breccia; primarily microcrystalline quartz (SiO₂) with iron oxides/hydroxides

Tumbled picture jasper

Microcrystalline quartz (SiO₂), commonly with iron-oxide and clay inclusions

Garnet

Silicate mineral group (e.g., Almandine, Fe3Al2(SiO4)3)

Quartzite

SiO2 (Silicon Dioxide)

Sandstone or Mudstone

Sedimentary Rock

Chalcopyrite

Chalcopyrite (CuFeS2)

Red Sandstone

Sandstone (hematitic/iron-rich quartzite or arenite)

Anthracite coal (likely)

Anthracite; carbon-rich coal composed mainly of maceral vitrinite, with variable mineral impurities

Iron-stained quartz-rich rock (possibly ironstone)

Quartz (SiO₂) with iron-oxide/hydroxide staining, likely limonite/goethite

Polished pietersite cabochon

Pietersite (brecciated fibrous quartz/chalcedony, commonly with riebeckite or crocidolite remnants)