Organic Gem Material (Botanical)

Quartz

Silicon Dioxide (SiO2)

Fossilized Bone

Permineralized Vertebrate Bone

Jasper

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Amber

Succinite (Fossilized Tree Resin)

Peridotite (Olivine Rock)

Peridotite (composed largely of olivine, (Mg, Fe)2SiO4)

Garnet (Rough Almandine Crystal)

Almandine Garnet (Fe3Al2(SiO4)3)

Jadeite

Jadeite (NaAlSi2O6)

Rough Emerald

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Nephrite Jade

Ca2(Mg,Fe)5Si8O22(OH)2

Aura Quartz

Titanium-coated Silicon Dioxide (SiO2)

Turquoise Beads

CuAl6(PO4)4(OH)8·4H2O

Weathered quartz-rich metamorphic rock, likely gneiss or quartzite

Quartz (SiO₂)-bearing gneiss; exact identification requires a fresh surface and tests

Weathered greenstone pebble

Metamorphosed mafic rock, commonly metabasalt or greenschist (exact identification requires testing)

Green tourmaline (likely elbaite)

Tourmaline group; likely elbaite, complex borosilicate such as Na(Li,Al)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

Iron-rich quartzite or ironstone

Ferruginous quartzite; chiefly quartz (SiO₂) with iron oxides such as hematite and goethite

Weathered limestone or calcareous sandstone

Calcite-rich carbonate rock, chiefly calcium carbonate (CaCO₃), possibly fossiliferous limestone

Sapphire

Corundum (Al2O3)

Tumbled amethyst

Amethyst, purple quartz (SiO₂), colored by trace iron and irradiation

Tumbled green jasper or serpentine

Likely serpentine-group mineral, chiefly magnesium silicate; possibly epidotized or altered jasper

Chert (Chalcedony)

Microcrystalline Quartz (SiO2)

Small quartz crystal cluster (likely druzy quartz)

Quartz, silicon dioxide (SiO₂)

Mixed Polished Gemstones (Tumbled Stones)

Mixed Silicates and Oxides (SiO2, KAlSi3O8, Ca2Al2Be3Si6O22, etc.)

Chert (Flint Pebbles)

Chert (SiO2)

Iron-stained quartz/pegmatite fragment

Quartz (SiO₂) with iron-oxide/hydroxide staining, possibly feldspar matrix

Greenstone pebble, likely altered basalt

Metabasalt/greenstone; commonly chlorite–epidote–actinolite with albite and iron oxides

Tumbled green beryl or glassy green gemstone

Likely beryl, Be₃Al₂Si₆O₁₈; possibly treated emerald or synthetic glass

Weathered sandstone pebble

Quartz-rich sandstone; chiefly SiO₂ with possible feldspar, mica, and iron-oxide cement

Weathered quartz-rich rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly iron-oxide stained

Quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Blue-and-gold lapis lazuli fragment

Lapis lazuli; lazurite-rich calc-silicate rock (primarily lazurite, with calcite and pyrite)

Chrysocolla-bearing copper ore

Chrysocolla, hydrated copper phyllosilicate (approximately (Cu,Al)₂H₂Si₂O₅(OH)₄·nH₂O), likely mixed with malachite and/or turquoise

Freshwater Pearl

Calcium Carbonate (CaCO3) in the form of Aragonite and Calcite

Iron-stained chert or flint nodule

Microcrystalline quartz (SiO₂), likely chert with limonite/goethite staining

Jasper

Jasper (Silicified microcrystalline quartz) - SiO2

Tumbled cream chalcedony or quartz

Microcrystalline quartz, SiO₂; possibly iron-stained chalcedony

Turquoise in Matrix

Hydrated copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O

Likely weathered quartz-rich stone or fossil fragment

Indeterminate; possibly quartz-bearing sandstone, iron-stained quartz, or a fragmentary fossil

Rhodonite

Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3

Fossilized Bone

Vertebrate fossil (mineralized bone)

Red Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Polished tiger’s-eye pebble

Quartz (SiO₂), chatoyant fibrous variety; commonly partly altered crocidolite