Mineraloid (Human Made Geological Specimen)

Pearl necklace

Pearl, primarily aragonite (CaCO₃) and conchiolin

Polished amethyst bead fragments

Amethyst, purple quartz (SiO₂)

Chalcedony (likely blue agate) knapped into an arrowhead

Microcrystalline quartz, SiO₂ (chalcedony)

Limonite (Iron Ore)

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Limonite and Goethite (Ironstone)

Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)

Flint / Chert

Microcrystalline quartz (SiO2)

Heart-shaped faceted gemstone pendant

Likely yellow quartz (citrine) or synthetic yellow stone, set in metal with small clear accent stones

Black Pearl (Tahitian or Irradiated Type)

Organic gemstone (Calcium Carbonate with Conchiolin Binding)

Blue gemstone cross pendant

Likely faceted blue topaz (Al₂SiO₄(F,OH)₂); identification is uncertain from the image

Aura Quartz (Anomalously Coated Quartz)

Silicon Dioxide (SiO2) treated with vaporized metals

Cobalt Glass Slug (Cullet)

Man-made Silicate Glass with Cobalt Oxide (CoO)

Limonite (Iron Stone/Goethite)

Limonite (mixture of hydrated iron oxides, primarily Goethite: α-FeO(OH))

Chert Arrowhead

Cryptocrystalline quartz (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Quartz pebble in concrete

Quartz (SiO₂), embedded in Portland-cement concrete

Black-and-white agate or onyx bead necklace

Variegated chalcedony (microcrystalline SiO₂), possibly black-and-white banded agate; some black beads may be dyed chalcedony or hematite

Chert (Flint)

Microcrystalline Quartz (SiO2)

Sandstone (Pet Rock)

Clastic sedimentary rock (primarily SiO2)

Lemon (Mock specimen mimicking Citrine/Sulfur)

Citrus x limon

Baked-clay ceramic fragment (likely brick or pottery)

Fired clay, primarily aluminosilicate minerals; not a natural rock

Quartz (likely Chalcedony or Chert)

Silicon Dioxide (SiO2)

Opalite

Synthetic Opalized Glass (SiO2 + additives)

Faceted clear gemstone in a gold-colored setting

Unidentified transparent faceted stone; possibly quartz, glass, or another colorless gem

Polished orbicular granite

Orbicular granite, commonly quartz–feldspar–biotite granite with orbicules

Chert

Microcrystalline Quartz (SiO2)

Obsidian

Volcanic Glass

Gold ring with a clear faceted gemstone

Likely diamond (crystalline carbon, C); identification is uncertain from the image

Opalite

Synthetic Opalised Glass

Chert (Flint)

SiO2 (Microcrystalline Quartz)

Blue Goldstone

Man-made glass with crystalline copper/cobalt inclusions

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Limonite (Ironstone Concretion)

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

Opalite

Synthetic Opalite Glass

Tumbled milky quartz pebble

Quartz (SiO₂), likely milky quartz

Uncertain small metallic-looking mineral/rock fragment

Indeterminate; possibly galena-bearing rock or metallic slag

Cullet (Slag Glass)

Amorphous Silica (Industrial byproduct)

Clear quartz crystal pendant

Quartz (silicon dioxide, SiO₂)

Limonite (Ironstone) Concretion

FeO(OH)·nH2O (Hydrous ferric oxide)

Blue glassy gemstone cabochon, likely dyed chalcedony or glass

Uncertain; possible dyed chalcedony (microcrystalline quartz, SiO₂)

Pink tumbled stone, likely dyed howlite or magnesite

Most likely magnesite (MgCO₃) or howlite [Ca₂B₅SiO₉(OH)₅], artificially dyed pink; exact identification requires testing.

Cowrie Shell Fossil

Cypraea sp.

Opalite

Synthetic glass (SiO2 + metal additions)