Man Made Composite

Chert Concretion (with typical hematite/limonite staining)

Sedimentary Concretion (SiO2 with FeO(OH)⋅nH2O)

Sandstone Concretion

Clastic Sedimentary Rock (primarily SiO2 with mineral cement)

Pyrite Concretion (Grapestone)

Iron Sulfide (FeS2) Concretion

Cubic Zirconia (Simulated Diamond)

Cubic Zirconia (ZrO2)

Opalite

Synthetic Opalized Glass

Opalite

Synthetic Opalite Glass (Silicon Dioxide)

Blue Glass or Slag Glass

Amorphous Silica (Anthropogenic Glass)

Cubic Zirconia (Man-made)

Cubic Zirconia (ZrO2) with Enamel and Metal Alloy

Black glassy fragment, likely obsidian or industrial glass

Volcanic glass (obsidian), chiefly amorphous SiO₂; identification uncertain from image

Sandstone (with man-made markings)

Arenite (composed primarily of Quartz, SiO2)

Blue Goldstone

Goldstone (artificial glass)

Aura Quartz (Titanium/Gold coated)

Silicon Dioxide (SiO2) with metallic vapor deposition

Polished white chalcedony or quartz pendant

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

Iron Slag

Iron/Steel Slag (Ferrosilicate Glass)

Iron Slag (Industrial Byproduct)

Anthropogenic Vitrification Product/Ferrous Slag

Slag Glass

SiO2 (Silicon Dioxide) with impurities

Opalite

Synthetic Glass, SiO2 base with metallic inclusions

Blue Goldstone

Man-made glass with suspended copper, cobalt, or manganese particles

Black Obsidian

Amorphous volcanic glass (SiO2 + impurities)

Clear quartz fragment (rock crystal)

Quartz, silicon dioxide (SiO₂)

Blue opal heart cabochon

Common opal, hydrated amorphous silica (SiO₂·nH₂O), likely blue-dyed or synthetic opalite

Slag (Industrial Glass/Glassy Rock)

Anthropogenic Vitreous Material

Sea Glass (White/Clear)

Amorphous Silica (Alkali-Lime-Silica Glass), SiO2 + Na2O + CaO

Aura Quartz

Titanium/Titanium-Gold treated Silicon Dioxide (SiO2)

Red Slag Glass

Amorphous Silica (Industrial byproduct with metallic oxide dopants)

Metal Alloy (Likely Pewter or Sterling Silver)

Not a natural geological specimen; composed of refined metals. If pewter, it's a tin-based alloy. If sterling silver, it's 92.5% silver and 7.5% other metals (usually copper).

Baked-clay ceramic fragment (likely brick or pottery)

Fired clay, primarily aluminosilicate minerals; not a natural rock

Conglomerate

Conglomerate Rock (Paraconglomerate)

Sandstone Concretion

Clastic sedimentary rock (primarily Quartz SiO2)

Green Aventurine

Quartzite with Fuchsite inclusions (SiO2 + K(Al,Cr)2(AlSi3O10)(OH)2)

Slag

Ferrous Slag (Amorphous calcium-magnesium-aluminum silicates)

Opalite

Synthetic Opalised Glass

Carborundum (Silicon Carbide)

Silicon Carbide (SiC)

Sea Glass

Amorphous silicon dioxide (SiO2) - Man-made glass tumbled by nature

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Titanium Amethyst Geode

Silicon Dioxide (SiO2) with Titanium/Metal Vapor Deposition Layer

Polished silver sheen obsidian heart

Obsidian (volcanic glass), primarily rhyolitic silica-rich glass

Red-orange cabochon, likely carnelian or glass imitation

Carnelian: chalcedony (microcrystalline SiO₂), commonly iron-colored

Green Glass (often marketed as 'Obsidian' or 'Green Quartz')

Amorphous Silica (SiO2) with copper or chromium additives

Pet Rock (Man-made Quartzite or Granite Cobble)

Silicon dioxide (SiO2) mixture; commonly composed of Quartz, Feldspar, and Mica

Blue-green cabochon, likely chalcedony or treated glass imitation

Cryptocrystalline quartz (chalcedony/possibly chrysoprase); identification uncertain from image

Blue Obsidian

Volcanic Glass (SiO2 with inclusions)