Anthropogenic (Man Made Product Subject To Geological Processes)

Small reddish-brown pebble, possibly jasper or iron-stained quartz

Unidentified silica-rich pebble; visual identification is insufficient to distinguish jasper, quartz, or another material

Quartzite

Metamorphosed Quartz Sandstone

Pegmatitic granite specimen

Granitic pegmatite, chiefly quartz (SiO₂), feldspar, and mica

Collection of Minerals and Ores

Various (e.g., Uraninite (U3O8), Carbon (C), Native Gold (Au), Hematite (Fe2O3), Galena (PbS), etc.)

Quartzite Cobble

Metamorphosed Quartz Sandstone (SiO2)

Pink Marble

Recrystallized Limestone (Calcium Carbonate, CaCO3)

Polished orbicular jasper (likely ocean jasper)

Siliceous microcrystalline quartz/chalcedony aggregate; commonly sold as Ocean Jasper

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Chalcedony (likely brown agate or flint)

Microcrystalline quartz, SiO₂; chalcedony, possibly iron-stained

Sandstone (likely a river or beach pebble)

Sandstone (a clastic sedimentary rock)

Pyrite

Iron Sulfide (FeS2)

Tumbled red-brown stone, possibly carnelian

Likely chalcedony (microcrystalline quartz, SiO₂); identification from the image is uncertain

The user-provided image does not contain a rock or mineral specimen

Polished carnelian agate pendant

Microcrystalline quartz (SiO₂), orange chalcedony; likely banded agate

Coal (Bituminous Coal)

Caustobiolith / Sedimentary Rock

Tumbled yellow jasper

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

Sandstone (Ferruginous)

Arenite (with Iron Oxide cement)

Quartzite

Quartzite (SiO2)

Chalk

Micrite (primarily Calcium Carbonate or CaCO3)

Granite-like rock

Likely weathered granite or granitic pegmatite; chiefly quartz, feldspar, and minor mica

Basalt with Iron Oxide staining

Basalt (Mafic volcanic rock)

Iron-rich concretion or slag-like mineral fragment

Likely limonite/goethite (FeO(OH)·nH₂O), possibly magnetite-bearing material

Veined Limestone

Calcite-veined Limestone (CaCO3)

Red-brown iron-rich mineral specimen, likely hematite/goethite

Hematite (Fe₂O₃), possibly mixed with goethite (FeO(OH)) and iron oxides

Red Sandstone

Arenite (Ferruginous Sandstone)

Tumbled red jasper

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

Polished brecciated jasper

Jasper, microcrystalline quartz (SiO₂), with iron-oxide and dark mineral inclusions

Tumbled quartz-rich rock, likely quartzite or milky quartz with iron-oxide staining

Quartzite (primarily SiO₂), possibly with hematite/goethite staining and minor feldspar or mica

Weathered quartz-rich rock, possibly quartzite or silicified sandstone

Quartz-dominant aggregate; likely microcrystalline quartz (SiO₂), but exact identification requires testing

Coal

Bituminous Coal (organic sedimentary rock)

Polished agate (likely moss agate)

Microcrystalline quartz, SiO₂ (chalcedony); possible moss-like inclusions

Honey-brown calcite crystal cluster

Calcite (CaCO₃), likely dogtooth or scalenohedral calcite

Quartzite Pebble

Si02 (Metamorphosed Sandstone)

Bituminous Coal

Coal (Sedimentary Rock)

Colorless faceted gemstones, likely quartz (rock crystal)

Quartz, silicon dioxide (SiO₂), trigonal crystal system

Tumbled pink chalcedony (likely pink agate)

Chalcedony, microcrystalline SiO₂; variety of quartz

Aragonite

Aragonite (Calcium Carbonate - CaCO3)

Tumbled serpentine

Serpentinite; chiefly antigorite, lizardite, or chrysotile Mg₃Si₂O₅(OH)₄, with possible magnetite and carbonate

Coal

Anthracite or Bituminous Coal

Quartzite

Quartzite (primarily SiO2)

Quartzite

Quartzite (SiO2)

Quartzite Pebble

Quartzite (SiO2)