Organic Gemstone (Not A Rock Or Mineral In The Traditional Sense, But Bio Mineralized Material)

Polished plume agate

Chalcedony (microcrystalline SiO₂) with iron-oxide inclusions

Sandstone

Arenite (SiO2 composed primarily of quartz)

Chert

Silicon dioxide (SiO2)

Dendritic jasper/chalcedony

Silica-rich microcrystalline quartz (SiO₂) with manganese-oxide dendrites

Pearl (as a biogenic mineral/gemstone)

Calcium Carbonate (mostly Aragonite), CaCO3

Poppy Jasper

Microcrystalline Quartz (SiO2) with mineral inclusions

Petrified Wood

Silicified Wood (SiO2)

Amber

Fossilized Tree Resin (C10H16O)

Hessonite Garnet (Grossular)

Ca3Al2(SiO4)3 (Grossular Garnet)

Anthracite Coal

Anthracite (a variety of coal, predominantly carbon)

Fossilized Bone

Permineralized Vertebrate Bone

Vesicular volcanic scoria (likely basaltic scoria)

Scoria; predominantly vesicular basalt, composed mainly of plagioclase, pyroxene, and iron-rich glass

Drusy quartz cluster (likely quartz on a pale host rock)

Quartz, silicon dioxide (SiO₂), likely microcrystalline/drusy quartz

Fossilized bone

Petrified bone; commonly fossil vertebrate bone composed largely of hydroxyapatite and silica/calcite replacement minerals

Quartz-veined Limestone

Sedimentary limestone with quartz/calcite veinlets

Scoria (Volcanic Rock)

Scoria (often basaltic scoria)

Shark Tooth Fossil

Vertebrate fossilized tooth (various genera such as Carcharodon, Otodus, or Negaprion)

Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

Petrified Wood

Silicified Wood (SiO2)

Amethyst cabochon ring

Amethyst, purple quartz (SiO₂), colored primarily by iron-related defects and irradiation

Red Coral

Corallium rubrum (Calcium Carbonate, CaCO3)

Green Calcite

Calcite (CaCO3)

Tiger's Eye (Jasper-like Chalcedony)

Silicon dioxide (SiO2) - Pseudomorph after Crocidolite

Blue Zircon

Zircon (Zirconium Silicate), ZrSiO4

Quartz-veined metamorphic rock, likely greenschist or altered metavolcanic

Chlorite–actinolite–epidote-bearing metavolcanic rock with quartz veins; exact identification requires testing

Fossiliferous shale or mudstone with plant fossils

Carbonaceous mudstone/shale containing fossilized foliage, likely fern or seed-fern impressions

Polished pink-orange chalcedony (likely carnelian)

Microcrystalline quartz, SiO₂; carnelian is orange-red chalcedony

Fossil gastropod shell

Fossilized marine gastropod; exact genus/species cannot be determined from the image

Quartz vein in host rock

Quartz (SiO₂), likely in a weathered carbonate or sedimentary matrix

Sandstone

Sandstone (SiO2-dominated clastic rock)

Fossilized bone fragment

Petrified bone, mineral-replaced vertebrate bone; exact taxon indeterminate

Sandstone

Arenite

Sandstone

Arenite

Polished bloodstone (heliotrope)

Chalcedony, microcrystalline quartz (SiO₂) with iron-oxide inclusions

Shark Tooth Fossil

Chondrichthyes (class) fossilized tooth

Emerald-like green beryl fragment

Beryl, Be₃Al₂Si₆O₁₈; green color typically from chromium or vanadium

Moss agate bracelet

Chalcedony (microcrystalline quartz, SiO₂) with chlorite/amphibole inclusions

Sedimentary Sandstone

Arenite (Sedimentary Rock)

Fossil gastropod shell

Fossilized gastropod, likely a small marine snail; exact genus cannot be determined from the image

Emerald

Beryl (Be3Al2(SiO3)6)

Quartz-rich geode or mineralized cavity in host rock

Likely a quartz-bearing geode; the pale crystals may be quartz (SiO₂), but the photo is not detailed enough for a firm identification.

Cantera Opal (Mexican Matrix Opal)

Hydrated silica in rhyolite host rock (SiO2·nH2O in Rhyolite)