Mineraloid (Human Made Geological Specimen)

Greenstone / serpentinite carving

Serpentinite, chiefly serpentine-group minerals (antigorite, lizardite, or chrysotile); exact identification requires testing

Opalite

Synthetic Opalite Glass (Silicon Dioxide)

Opalite

Man-made Glass (SiO2 + additives)

Green glassy slag (often sold as “sea glass” or “green obsidian”)

Industrial vitreous slag; primarily amorphous silicate glass, composition variable

Limonite (Ironstone)

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

Obsidian

Volcanic Glass (Silica-rich, SiO2)

Beaded bracelet, likely green aventurine and yellow citrine or dyed quartz

Quartz, SiO₂ (green aventurine may contain fuchsite inclusions)

Not a rock, mineral, or geological specimen

Aluminum Slag

Anthropogenic Aluminum (Al)

Banded agate cabochon

Microcrystalline quartz (chalcedony), SiO₂

Tumbled fossil shark tooth pendant

Likely fossilized shark tooth, possibly Otodus or Carcharhinus; exact species cannot be confirmed from the image

Amethyst gemstone ring

Quartz, purple variety — SiO₂

Chert (Common Opal/Jasper variety)

Cryptocrystalline Quartz (SiO2)

One Pound Coin (UK)

Nickel-Brass Alloy (Cu-Zn-Ni)

Chert Arrowhead

Cryptocrystalline Quartz (SiO2)

Opalite

Synthetic Opalized Glass

Pearl-and-gemstone insect brooch

Pearl: nacre (aragonite, CaCO₃); colored stones are likely synthetic or natural corundum/spinel/glass, not determinable from the image

Native silver fragment (probable)

Silver, Ag; possibly silver-bearing sulfide or plated metal

Dyed Quartz Cube

Silicon Dioxide (SiO2)

Tumbled clear quartz (rock crystal)

Quartz, silicon dioxide (SiO₂)

Banded agate pendant (likely carnelian or brown-and-white chalcedony agate)

Agate, a banded variety of chalcedony; microcrystalline quartz, SiO₂, with iron-oxide coloration

Obsidian

Volcanic Glass

Chert (Yellow Jasper/Flint)

Chert (Microcrystalline Silicon Dioxide, SiO2)

Carnelian cabochon pendant

Carnelian, orange-red chalcedony (microcrystalline quartz, SiO₂)

Concrete

Anthropogenic Sedimentary Rock (Hydrated Calcium Silicate)

Goldstone and pink quartz bead strands

Goldstone is aventurescent copper-bearing glass; pink beads are likely rose quartz (SiO₂), though dyed or glass imitations are possible

Tumbled yellow jasper or chalcedony

Microcrystalline quartz, SiO₂; likely iron-oxide-bearing jasper/chalcedony

Polished blue-green jasper beads

Jasper, an opaque microcrystalline variety of quartz (SiO₂)

Sea Glass

Anthropogenic Silicate Glass

Blue faceted gemstone, likely synthetic sapphire or blue glass

Corundum (Al₂O₃) if sapphire; identity cannot be confirmed visually

Polished dark gray stone, likely basalt or fine-grained andesite

Basalt/andesite; primarily plagioclase feldspar, pyroxene, and possibly olivine or magnetite

Dark rounded pebble, likely basalt or slag

Probable fine-grained mafic rock; possibly basalt (plagioclase–pyroxene) or industrial iron/steel slag

Chert (varietal Chalcedony or Flint)

Silicon dioxide (SiO2) - Microcrystalline Quartz

Concrete aggregate surface

Human-made cementitious composite; primarily calcium-silicate-hydrate cement with mixed silicate aggregate

Sandstone (with concrete/human-made layer)

Clastic Sedimentary Rock (primarily Quartz/Feldspar grains)

Green jasper (possibly dyed or coated)

Microcrystalline quartz, SiO₂; jasper is an opaque variety of chalcedony

Flint (or Chert with cortex)

Silicon dioxide (SiO2)

Yellow Ocher (Limonite)

Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O

Polished black stone, likely black obsidian

Volcanic glass; predominantly rhyolitic silica glass (SiO₂-rich)

Likely weathered granite or granitic gneiss fragment

Granite; primarily quartz, feldspar, and mica

Sea Glass

Man-made vitreous material / Silicon dioxide

Fossil shark tooth, likely megalodon

Fossilized shark tooth; possibly Otodus megalodon (formerly Carcharocles megalodon)