Mineraloid (Human Made Geological Specimen)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Black Pearl (Tahitian or Irradiated Type)

Organic gemstone (Calcium Carbonate with Conchiolin Binding)

Quartz (likely Chalcedony or Chert)

Silicon Dioxide (SiO2)

Baked-clay ceramic fragment (likely brick or pottery)

Fired clay, primarily aluminosilicate minerals; not a natural rock

Limonite (Ironstone) Concretion

FeO(OH)·nH2O (Hydrous ferric oxide)

Uncertain small metallic-looking mineral/rock fragment

Indeterminate; possibly galena-bearing rock or metallic slag

Chert

Microcrystalline Quartz (SiO2)

Opalite

Synthetic Opalized Glass (SiO2 + additives)

Chert (Flint)

SiO2 (Microcrystalline Quartz)

Blue Goldstone

Man-made glass with crystalline copper/cobalt inclusions

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Opalite

Synthetic Opalised Glass

Clear quartz crystal pendant

Quartz (silicon dioxide, SiO₂)

Tumbled milky quartz pebble

Quartz (SiO₂), likely milky quartz

Cowrie Shell Fossil

Cypraea sp.

Limonite Concretion

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Cobalt Glass Slug (Cullet)

Man-made Silicate Glass with Cobalt Oxide (CoO)

Chert (or Flint)

Chert (a cryptocrystalline variety of quartz, SiO2)

Limonite (Ironstone Concretion)

Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)

Opalite

Synthetic Opalite Glass

Tumbled quartz or calcite specimen

Quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing

Pearl-embellished decorative cross

Pearl (biogenic calcium carbonate, predominantly aragonite) with rhinestone-mounted glass or synthetic gemstones

Multicolored beryl gemstone bracelet

Beryl, Be₃Al₂Si₆O₁₈; likely mixed aquamarine, morganite, heliodor, and green beryl beads

Blue glassy gemstone cabochon, likely dyed chalcedony or glass

Uncertain; possible dyed chalcedony (microcrystalline quartz, SiO₂)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Asphalt (Road Aggregate)

Bituminous Conglomerate / Asphalt Concrete

Polished orbicular jasper (likely ocean jasper)

Siliceous microcrystalline quartz/chalcedony with iron-oxide and volcanic inclusions; commonly called ocean jasper

Colorless faceted gemstone, likely glass or cubic zirconia

Uncertain; possible cubic zirconia (ZrO₂) or quartz (SiO₂), but the image may show a man-made simulant

Polished dark gemstone, likely hematite or magnetite

Hematite (Fe₂O₃) or magnetite (Fe₃O₄); exact identification requires testing

Cullet (Slag Glass)

Amorphous Silica (Industrial byproduct)

Green Slag

Anthropogenic Silicate Glass

Goldstone and Aura Quartz

Cuprous Glass (Goldstone) and Titanium-coated SiO2 (Aura Quartz)

Dyed Quartz (often sold as 'Blue Quartz' or 'Blue Agate')

Silicon Dioxide (SiO2) with artificial pigment

Colorless faceted gemstone, likely glass or quartz

Uncertain; possibly quartz (SiO₂), but the strong uniform brilliance and apparent molded/faceted form may indicate leaded glass or cubic zirconia

Faceted gemstone pendant, likely quartz or citrine

Indeterminate from photograph; likely quartz (SiO₂), possibly yellow citrine or treated quartz

Precious Coral (Red Coral)

Corallium rubrum (Calcium Carbonate, CaCO3)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert / Flint Tool

Cryptocrystalline quartz (SiO2)

Gold (Elemental Metal)

Gold (Au)

Chert (Flint)

Silicon dioxide (SiO2)

Opalite

Synthetic glass (SiO2 + metal additions)

Exposed Aggregate Concrete (Pea Gravel)

Concrete with Siliceous Alluvial Gravels