Mineral With Artificial Coating

Weathered granitic rock (likely granite or granodiorite)

Granite–granodiorite; mainly quartz, feldspar, and dark mica/amphibole

Likely weathered volcanic rock (possibly basalt)

Basalt, a fine-grained mafic igneous rock; exact identification is uncertain from the photograph

Small rounded yellow pebble, likely quartz-rich rock

Indeterminate from image; possibly iron-stained quartz or chert

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and mica (exact identification is uncertain from the photograph)

Quartz Pebble (Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock; chiefly plagioclase, pyroxene, and commonly olivine

Weathered sandstone or iron-stained siltstone

Quartz-rich clastic sedimentary rock, likely ferruginous sandstone

Copper-bearing rock, likely bornite/chalcopyrite ore in quartz matrix

Bornite (Cu₅FeS₄) and/or chalcopyrite (CuFeS₂), with quartz (SiO₂) and dark gangue minerals

Likely quartz-rich rock fragment

Quartz (SiO₂), possibly in a feldspar-bearing granite or pegmatite matrix

Polished blue-green metallic mineral specimen, likely bornite (“peacock ore”)

Bornite, Cu₅FeS₄; possibly chalcopyrite, CuFeS₂, with iridescent tarnish

Banded Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Weathered River Rock (likely Chert or Basalt with algae)

Silicon dioxide (SiO2) with organic biofilm

Copper Ore (Malachite and Azurite on Host Rock)

Cuprite, Malachite, and Azurite dissemination in gangue

Quartz Geode (with possible Manganese or Goethite coating)

Silicon Dioxide (SiO2)

Botryoidal quartz (likely milky quartz)

Quartz, silicon dioxide (SiO₂)

Healer's Gold (Iron-Stained Quartz Cluster)

Silicon Dioxide with Iron Oxide Coating (SiO2)

Raw quartz crystal/chunk

Quartz (silicon dioxide, SiO₂)

Amethyst druzy quartz with calcite and gray matrix

Quartz, SiO₂ (amethyst variety), with probable calcite, CaCO₃

Blue-gray chalcedony geode with druzy quartz

Microcrystalline quartz (SiO₂), with quartz druse; possibly agate/chalcedony

Tumbled dark blue-green stone, likely blue apatite or indigo gabbro

Apatite, Ca5(PO4)3(F,Cl,OH), or possibly quartz-rich indigo gabbro

Blue quartz (likely dyed or synthetic-treated quartz beads)

Quartz, silicon dioxide (SiO₂)

Polished purple quartz (likely amethyst)

Amethyst, a purple variety of quartz (SiO₂), possibly with iron-oxide staining or matrix

Quartz with iron-oxide staining, possibly associated with calcite

Quartz (SiO₂), with limonite/goethite (hydrated iron oxides) and probable calcite (CaCO₃)

Quartz druzy geode

Quartz, silicon dioxide (SiO₂), microcrystalline/druzy variety

Tangerine Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite coatings

Iron-Stained Quartz (Red/Hematoid Quartz)

Silicon Dioxide (SiO2) with Hematite/Goethite inclusions

Granite Pebble (Pink Feldspar-rich)

Granite

Moqui Marble (Concretion)

Iron Oxide Concretion

Fossil Shark Tooth

Selachii (fossilized dentition)

Red Siltstone (or Red Shale)

Clastic Sedimentary Rock (Composition: primarily Quartz, Clay minerals, and Hematite Fe2O3)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Dyed Agate (Tumbled)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Amethyst (Agate/Chalcedony variety)

Silicon Dioxide (SiO2) with iron impurities

Citrine (Iron-stained Quartz)

Silicon Dioxide (SiO2)

Carnelian and Dyed Agate

Chalcedony (Silicon Dioxide, SiO2)

Selenite desert rose

Gypsum (CaSO₄·2H₂O), rosette habit

Ferruginous Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Ferruginous Quartz (Iron-stained Quartz)

Silicon Dioxide with Iron Oxide (SiO2 with traces of Fe2O3/FeO(OH))

Tumbled quartz-rich feldspathic rock, possibly granite or granitic gneiss

Quartz–feldspar aggregate; likely granitoid (quartz + feldspar ± mica and iron-oxide staining)

Copper-bearing sulfide ore, likely chalcopyrite with iron oxides

Chalcopyrite (CuFeS₂), possibly associated with bornite (Cu₅FeS₄), pyrite, and limonite/goethite

Tumbled quartz pebble with iron-oxide inclusions

Quartz (SiO₂), stained by hematite/goethite

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine