Organic Gem Material (Botanical)

Pearl (Biogenic Mineral)

Calcium Carbonate (primarily Aragonite) with Conchiolin; CaCO3

Limestone and Quartz Gravel with Petrified Wood

Sedimentary gravel aggregate and fossilized wood

Jasper

Microcrystalline Quartz (SiO2)

Fossil Shark Tooth

Chondrichthyes (Class)

Black Onyx and Mother of Pearl

Cryptocrystalline Quartz (SiO2) and Nacre (Calcium Carbonate)

Red Jasper (River Siltstone)

Silicon Dioxide (SiO2) with iron oxide inclusions

Gemstone Sand (Mineral Assortment)

Mixed Mineral Concentrates (Commonly including Quartz SiO2, Garnet X3Y2(SiO4)3, and Tourmaline (Na,Ca)(Li,Mg,Al)3(Al,Fe,Mn)6(BO3)3(Si6O18)(OH,F)4)

Tumbled smoky quartz

Quartz, silicon dioxide (SiO₂), smoky variety

Rounded river cobble, likely basaltic volcanic rock

Fine-grained mafic igneous rock; likely basalt or andesite

Tumbled quartz-rich stone, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite (recrystallized quartz sandstone)

Quartz-rich sandstone or quartzite

Quartzite; predominantly crystalline SiO₂, possibly with feldspar and iron-oxide staining

Milky quartz-bearing rock, likely quartzite or silicified limestone

Quartz (SiO₂), possibly in a quartzite or chalcedony-rich matrix

Dark metamorphic rock, likely biotite schist or gneiss

Quartz–feldspar–biotite metamorphic rock; exact identification requires a fresh surface and testing

Olivine (often within Peridotite)

Magnesium iron silicate, (Mg,Fe)2SiO4

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Cubic Zirconia

Zirconium dioxide (ZrO2)

Chert / Flint

Microcrystalline Quartz (SiO2)

Fossilized Bone Fragment

Vertebrate Fossil

Turquoise

Turquoise (CuAl6(PO4)4(OH)8·4H2O)

Amber

Succinite

Botryoidal hematite/goethite specimen

Hematite (Fe₂O₃), likely with goethite (FeO(OH)) and minor limonite

Botryoidal hematite/goethite specimen

Hematite (Fe₂O₃), likely mixed with goethite (FeO(OH))

Petrified Wood

Silicified Wood (SiO2)

Mother of Pearl (Nacre)

Aragonite (CaCO3) with Organic Matrix

Tumbled dark green stone, likely greenstone/serpentinite

Serpentinite (serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄), possibly chlorite-rich greenstone

Amethyst quartz fragment

Quartz, silicon dioxide (SiO₂), purple variety colored primarily by iron impurities and irradiation

Likely polished garnet fragment

Garnet group, possibly almandine (Fe₃Al₂Si₃O₁₂)

Rounded quartz-rich pebble

Likely quartzite or quartz-bearing sandstone; composition mainly SiO₂ with possible feldspar and iron-oxide impurities

Diamond (Cut Specimen)

Diamond (pure carbon, C)

Possible weathered sandstone or iron-rich sedimentary rock

Indeterminate; likely quartz-rich sandstone with iron-oxide cement

Sodalite beads

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂, likely with minor lazurite/pyrite or calcite inclusions

Garnet (Almandine)

Almandine (Fe3Al2(SiO4)3)

Sapphire

Corundum (Al2O3)

Likely weathered granite or granitic rock

Felsic intrusive igneous rock; quartz–alkali feldspar–plagioclase with biotite/hornblende

Pillow basalt (likely metamorphosed basalt/greenstone)

Basalt, commonly altered to chlorite–actinolite–epidote greenstone

Possible dark igneous rock

Indeterminate; likely basalt or fine-grained mafic rock

Raw calcite specimen

Calcite, calcium carbonate (CaCO₃)

Weathered, quartz-rich metamorphic rock (likely schist or gneiss)

Quartz–feldspar–mica schist/gneiss, with surface lichens and iron-oxide staining

Weathered fine-grained stone, likely sandstone or quartzite

Quartz-rich sandstone (possibly weakly metamorphosed quartzite); predominantly SiO₂

Chert (Jasper/Limonitic Chert)

Cryptocrystalline Quartz (SiO2) with Iron Oxide (FeO(OH)) inclusions

Peridot (Olivine)

Olivine (Magnesium Iron Silicate), (Mg,Fe)2SiO4

Olivine

Olivine group (Mg, Fe)2SiO4