Organic Gemstone (Sedimentary Classification)

Red Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

Pearls

Pearl: biomineralized aragonite (CaCO₃) and conchiolin

Bituminous Coal (with Anthracite or Vitrinite inclusion)

Organic-rich Sedimentary Rock (Carboniferous classification)

Red coral earrings

Corallium rubrum or related precious coral (calcareous coral skeleton; primarily aragonite, CaCO₃)

Small weathered mineral/rock fragment

Indeterminate; possibly quartz-bearing feldspathic rock or calcite-rich specimen

Petrified wood

Silicified wood; commonly quartz/chalcedony (SiO₂) replacing organic tissue

Likely anthracite coal fragments

Anthracite; predominantly carbon (C), with minor mineral ash

Banded gneiss

Gneiss, typically quartz–feldspar–mica ± amphibole

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, potentially granitic, or recrystallized quartzite

Mixed Rock and Mineral Collection

Various geological specimens

Anthracite coal

Anthracite; predominantly carbon (C), with minor mineral impurities

Likely mica-rich granite pegmatite

Granitic pegmatite, composed mainly of quartz and feldspar with visible mica (likely muscovite or biotite)

Polished red gemstone pendant, likely red jasper or brecciated jasper

Jasper: microcrystalline quartz (SiO₂), commonly with hematite or iron-oxide inclusions

Coarse-grained metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss (probable; exact identification requires a fresh surface and tests)

Quartz-rich pegmatite or quartz vein rock

Milky quartz (SiO₂), likely with iron-oxide staining and minor feldspar

Polished kambaba jasper

Orbicular stromatolitic jasper; microcrystalline quartz (SiO₂) with chlorite/amphibole-rich inclusions

Conglomeratic breccia

Clast-supported polymictic conglomerate/breccia, cemented by silica- or carbonate-rich matrix

Amber

Succinates (Organic Gemstone)

Red Siltstone

Siltstone (composed mainly of SiO2 and Fe2O3)

Pearl necklace

Pearl, primarily aragonite (CaCO₃) and conchiolin

Ammonite Fossil

Ammonoidea

Quartz-bearing dark rock, possibly hornfels or basalt

Probable quartz–feldspar rock; exact identification requires testing

Weathered Sedimentary Rock

Sedimentary Rock

Weathered iron-rich rock, possibly banded iron formation

Hematite–goethite-rich ironstone; possible BIF (Fe₂O₃/FeO(OH) with quartz)

Iron Meteorite

Siderite (Iron-Nickel alloy)

Amber

Succinrite (Organic Gemstone)

Iron Meteorite

Siderite (Iron-Nickel Alloy)

Iron Meteorite

Siderite (Iron-Nickel Alloy)

Lunar Breccia Meteorite

Lunar Feldspathic Breccia

Moss Agate

Silicon Dioxide with inclusions (SiO2 + impurities)

Blue opalite (often sold as synthetic opal)

Opalite glass; amorphous hydrated silica if natural opal (SiO₂·nH₂O)

Sandstone

Arenite (Secondary classification based on grain size)

Weathered quartz-rich rock, possibly chert or quartzite

Likely microcrystalline quartz (SiO₂), but exact identification is uncertain from the photograph

Iron-rich breccia or weathered limonite-bearing rock

Goethite–limonite ironstone, possibly ferruginous breccia

Gray rock (possibly basalt or fine-grained granite)

Undetermined; no diagnostic minerals are visible

Zebra Jasper

Tektite variety of Silicon Dioxide (SiO2) with inclusions

Chondrite Meteorite

L or H Ordinary Chondrite

Lunar Meteorite (Feldspathic Breccia)

Lunar Feldspathic Breccia

Milky quartz-bearing rock, possibly quartzite

Quartz (SiO₂), likely in a quartzite or quartz-rich vein

Rough Amber (likely Copal or immature Amber)

Organic gemstone / Succinite (if Baltic)

Amber

Succinicum (C10H16O)

Sandstone Cobble

Arenite (Secondary classification based on grain size)