Not A Natural Rock (Man Made Composite)

Terracotta (Man-made ceramic brick fragment)

Baked clay / High-iron ceramic (Silicate-based ceramic)

Sandstone

Arenite (SiO2, often with CaCO3 or Fe2O3 cement)

Diamond (likely) in an antique gold ring

Diamond, crystalline carbon (C)

Polished blue chalcedony (possibly agate)

Microcrystalline quartz, SiO₂; chalcedony, potentially banded agate

Unakite

Altered Granite (Epidotized Granite)

Likely polished quartz or glass-like mineral cabochon

Probably quartz (SiO₂), though the image cannot exclude man-made glass

Blue opalite (often sold as synthetic opal)

Opalite glass; amorphous hydrated silica if natural opal (SiO₂·nH₂O)

Diamond in Kimberlite

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

Diamond (Cluster Ring)

Carbon (C)

Coquina

Bioclastic Limestone (Coquina)

Polished turquoise cabochon jewelry (likely composite or stabilized turquoise)

Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O

Possible sea glass (naturally frosted glass), not a confirmed geological specimen

Man-made silicate glass; composition varies, commonly soda-lime glass

Bivalve shell fossil or modern shell

Calcareous bivalve shell, composed mainly of calcium carbonate (typically aragonite and/or calcite); species cannot be determined from this view

Dark quartz point (possibly smoky quartz)

Quartz, SiO₂; the dark color may indicate smoky quartz, but the image is insufficient to confirm

Red-orange sunstone (likely aventurine feldspar) bead bracelet

Feldspar, commonly oligoclase or labradorite with copper inclusions; composition varies by source

Blue Slag Glass

Amorphous Silica (Industrial byproduct)

Diamond

Carbon (C)

Diamond

Diamond (pure Carbon, C)

Rough Diamond

Pure Carbon (C)

Likely clear quartz crystal (possibly cut/polished quartz or glass imitation)

Quartz, silicon dioxide (SiO₂)

Mounted clear gemstone, likely cubic zirconia

Cubic zirconia (zirconium dioxide, ZrO₂), synthetic; exact stone cannot be confirmed from the image

Diamond

Carbon (C)

Turquoise bead bracelet

Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O; the beads may be treated or imitation material

Likely bismuth crystal

Synthetic bismuth (Bi), crystallized from molten metal; not a natural rock-forming specimen

Red coral (likely precious coral)

Corallium sp.; calcium-carbonate skeleton, primarily calcite

Polished brown chalcedony (likely carnelian or jasper)

Microcrystalline quartz, SiO₂; iron oxides produce the brown coloration

Polished agate bead bracelet

Agate, a banded microcrystalline variety of quartz (SiO₂), likely mixed-color dyed or naturally colored chalcedony

Black onyx bead necklace

Black chalcedony, a microcrystalline quartz variety (SiO₂); beads may be dyed or treated

Blue Slag Glass

Ferro-silicate glass (Slag)

Granite

Granite (a common rock type, not a single mineral with a formula. Composed primarily of quartz, feldspar, and mica/amphibole).

Sea glass (likely green bottle glass)

Human-made soda-lime silicate glass; not a natural mineral or geological rock

Fossil Turtle Shell

Testudines carapace fossil

Smoky Quartz

Smoky Quartz (SiO2)

Polished smoky quartz crystal point

Quartz (SiO₂), likely iron-colored or smoky quartz with milky inclusions

Aventurine

Aventurine Quartz (SiO2 with inclusions of Fuchsite)

Diamond

Carbon (C)

Diamond

Carbon (C)

Rough Diamond

Diamond (pure Carbon, C)

Coquina

Coquina (Bioclastic Limestone)

Granite (with a dark inclusion or attached fragment)

Granite, mainly quartz, feldspar, and mica; the dark object cannot be identified confidently from the photo.

Chert

Microcrystalline quartz (SiO2)

Chert

Microcrystalline Quartz (SiO2)