Antropogenic (Man Made)

Quartzite

Metamorphic Quartzite

Malachite

Malachite, Cu₂CO₃(OH)₂; a banded botryoidal copper carbonate specimen

Diamond

Carbon (C)

Diamond

C (Pure Carbon)

Fossilized Shell in Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Unidentified gray stone/concrete-like fragment

Indeterminate; likely a fine-grained carbonate or cementitious geological fragment

Asphalt aggregate (crushed stone in bitumen)

Artificial composite; predominantly crushed granite, basalt, limestone, and/or recycled aggregate bound by bitumen

Diamond in Kimberlite

Diamond in Kimberlite Matrix (Diamond: C, Kimberlite: complex Potassic Peridotite)

Chert (Siltstone / Flint)

SiO2 (Cryptocrystalline Quartz)

Limestone

Sedimentary Rock (Primarily CaCO3)

Basalt

Basalt (Mafic volcanic rock)

Quartzite

Quartzite (Metamorphosed Sandstone)

Quartzite

Metamorphic Quartzite (SiO2)

Basalt

Basalt (containing plagioclase, pyroxene, and olivine)

Fossilized Coral (Coquina/Limestone)

Cnidaria Anthozoa (Fossilized)

Weathered chert or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly silicified limestone or agate-like chalcedony

Diamond

Carbon (C)

Likely tumbled epidote-bearing rock or green jasper

Epidote-group silicate, possibly in a jasper or serpentinite matrix

Quartzite

Metamorphic Quartzite (SiO2)

Sandstone

Arenite (variable SiO2 composition)

Diamond

Carbon (C)

Goldstone (aventurine glass)

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

Tumbled chalcedony or quartz pebble

Microcrystalline quartz, SiO₂ (likely chalcedony); exact identification is uncertain from the image

Turquoise-style beaded bracelet

Turquoise, hydrated copper–aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O; possibly dyed or composite beads

Botryoidal chalcedony with iron-oxide staining

Microcrystalline quartz (SiO₂), likely iron-oxide-bearing chalcedony

Smoky Quartz Cluster

Smoky Quartz (Silicon Dioxide - SiO2)

Chalk

Calcium Carbonate (CaCO3)

Red Quartzite

Quartzite (Metamorphic quartz sandstone)

Aragonite

Aragonite (Calcium Carbonate - CaCO3)

Sandstone (Pebble)

Sandstone (SiO2 with matrix/cement)

Diamond

Carbon (C)

Diamond

Carbon (C)

Pearl

Aragonite (CaCO3 with conchiolin)

Diamond (in a jewelry setting)

Cubic Carbon (C)

Likely weathered sandstone fragment

Sandstone, composed mainly of quartz (SiO₂) and feldspar grains in a clay, silica, or iron-oxide cement

Diamond (faceted)

Diamond (Pure Carbon, C)

Quartzite

Metamorphic quartz rock (SiO2)

Quartzite

Metamorphic Quartzite (SiO2)

Pearl necklace

Pearl, primarily aragonite (CaCO₃) and conchiolin

Diamond

Carbon (C)