Mineralological Specimen

Limonite Geode / Ironstone Nodule

Hydrated Iron Oxide Hydroxide (FeO(OH)·nH2O)

Mixed rock and mineral collection

Unidentified assortment of geological specimens; individual species cannot be determined from the image

Unidentified polished mineral specimen

Indeterminate; likely a pale feldspar or quartz-bearing material

Schist

Mica Schist

Siltstone Pebble

Siltstone (fine-grained siliciclastic sedimentary rock)

Calcite crystal specimen

Calcite (CaCO₃)

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite, predominantly microcrystalline quartz (SiO₂), with iron-oxide staining and dark mica or amphibole inclusions

Likely basalt or vesicular volcanic rock

Basalt, possibly scoriaceous basalt; exact identification is uncertain from the photograph

Tumbled amethyst

Quartz, SiO₂; purple color typically from trace iron and natural irradiation

Milky quartz fragment

Quartz, silicon dioxide (SiO₂)

Diamond

Native Carbon (C)

Diamond

Natural Diamond (Carbon, C)

Diamond

Carbon (C)

Diamond (or Diamond Simulant)

Carbon (C)

Diamond (or Simulant)

Carbon (C)

Amethyst (rough quartz)

Quartz, SiO₂; purple variety colored mainly by iron impurities and irradiation

Diamond

Diamond (Pure Carbon - C)

Diamond

Diamond (C)

Diamond

C (Native Carbon)

Diamond

Carbon (C)

Diamond (in a gold setting)

Carbon (C)

Quartz Pebble

Silicon Dioxide (SiO2)

Peacock Ore (Bornite or Chalcopyrite)

Bornite (Cu5FeS4) or Acid-Washed Chalcopyrite (CuFeS2)

Quartz-veined Metamorphic Pebble

Silicate-rich metamorphic rock with quartz veins (SiO2)

Green Fluorite

Calcium fluoride (CaF2)

Tumbled Agate

Silicon Dioxide (Chalcedony / Quartz)

Milky quartz in dark host rock

Quartz (SiO₂), likely as a vein or vein fragment; host rock uncertain

Iron-stained quartz-rich rock, possibly goethite-bearing quartz

Quartz (SiO₂) with iron oxides/hydroxides, likely goethite or limonite

Quartz (with Iron staining)

Silicon Dioxide (SiO2)

Iron-rich basalt or weathered volcanic rock

Basalt, likely oxidized mafic volcanic rock; composition mainly plagioclase feldspar, pyroxene, and iron oxides

Biotite-bearing granite or granodiorite

Coarse-grained felsic intrusive rock; primarily quartz (SiO₂), feldspar, and biotite mica, possibly with hornblende

Granite

Granite; primarily quartz, alkali feldspar, plagioclase, and biotite/hornblende

Iron-rich concretion (possibly limonite/goethite)

Limonite, a mixture of iron oxyhydroxides, commonly including goethite (α-FeO(OH))

Tumbled serpentine

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

Green Fluorite (Botryoidal/Massive)

Calcium Fluoride (CaF2)

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2) with Hematite/Limonite

Fluorite on Matrix

Calcium Fluoride (CaF2)

Yellow Calcite

Calcite (Calcium Carbonate, CaCO3)

Weathered quartz-bearing rock, possibly druzy quartz or quartzite

Quartz (SiO₂), likely in a quartz-rich host rock; exact identification is uncertain from the photograph

Orange calcite (rough specimen)

Calcite, CaCO₃

Pyritic Quartzite

Quartzite with Pyrite inclusions (FeS2)

Native Copper with Malachite/Oxide Coating

Native Copper (Cu)