Anthropogenic (Man Made)

Basalt

Basalt (Mafic volcanic rock)

Diamond

Diamond (pure Carbon, C)

Diamond

C (Pure Carbon)

Diamond

Carbon (C)

Quartzite

Quartzite (Metamorphosed Sandstone)

Quartzite

Metamorphic Quartzite (SiO2)

Basalt

Basalt (containing plagioclase, pyroxene, and olivine)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Diamond

Carbon (C)

Chert (Siltstone / Flint)

SiO2 (Cryptocrystalline Quartz)

Sandstone

Sedimentary Rock (Quartz Sandstone)

Limestone

Sedimentary Rock (Primarily CaCO3)

Red Quartzite

Quartzite (Metamorphic quartz sandstone)

Aragonite

Aragonite (Calcium Carbonate - CaCO3)

Sandstone (Pebble)

Sandstone (SiO2 with matrix/cement)

Quartzite

Metamorphic Quartzite (SiO2)

Sandstone

Arenite (variable SiO2 composition)

Diamond

Carbon (C)

Diamond

Carbon (C)

Diamond

Carbon (C)

Goldstone (aventurine glass)

Synthetic copper-bearing soda-lime glass; commonly sold as red goldstone

Pearl

Aragonite (CaCO3 with conchiolin)

Fossilized Coral (Coquina/Limestone)

Cnidaria Anthozoa (Fossilized)

Chalk

Calcium Carbonate (CaCO3)

Raw calcite specimen

Calcite, calcium carbonate (CaCO₃)

Smoky Quartz Cluster

Smoky Quartz (Silicon Dioxide - SiO2)

Diamond (faceted)

Diamond (Pure Carbon, C)

Quartzite

Metamorphic quartz rock (SiO2)

Quartzite

Metamorphic Quartzite (SiO2)

Diamond (in a jewelry setting)

Cubic Carbon (C)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Nacre (Mother of Pearl)

Nacre (Biogenic Aragonite/Calcite composite, CaCO3)

Diamond

Carbon (C)

Sandstone (likely Fossiliferous)

Arenite / Fossiliferous Sandstone (SiO2 composition)

Quartzite

Metamorphic Quartz Arenite

Pearl

Calcium Carbonate (CaCO3) with Conchiolin

Sandstone

Arenite (specifically sublithic or quartz arenite)

Quartzite

Metamorphic Quartzite (SiO2)

Pyrite

Iron Sulfide (FeS2)

Diamond (Cluster Ring)

Carbon (C)

Diamond

Carbon (C)

Chert (Chert / Flint)

Microcrystalline Quartz (SiO2)