Man Made Material (Anthropogenic 'Mineraloid')

Flint (chert)

Microcrystalline quartz (SiO₂), a variety of chert

Ruby in Matrix

Corundum (Al2O3)

Tektite

Tektite (high-silica natural glass)

Polished mahogany obsidian

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

Mahogany Obsidian

Obsidian (Volcanic Glass with Hematite/Magnetite inclusions), SiO2

Red-orange sunstone (likely aventurine feldspar) bead bracelet

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

Slate

Metamorphic Pelitic Rock

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Chert or Jasper

Microcrystalline Quartz (SiO2)

Coquina

Bioclastic Limestone

Exposed aggregate concrete (stone-chip surface)

Portland-cement concrete containing natural aggregate; not a natural rock

Blue chalcedony cabochon (probable)

Chalcedony, a cryptocrystalline variety of quartz; silicon dioxide, SiO₂

Engraved purple stone cabochon, possibly amethyst

Unconfirmed; if amethyst, quartz (SiO₂)

Polished stromatolite (likely fossilized microbial mat)

Fossil stromatolite; chiefly microcrystalline quartz (SiO₂), commonly replacing carbonate

Quartzite Arrowhead (Archaeological Lithic)

Recrystallized Quartz (SiO2)

Chert (likely flint)

Microcrystalline quartz, SiO₂

Malachite

Malachite, Cu₂CO₃(OH)₂; a banded botryoidal copper carbonate specimen

Chert (Flint)

Silicon Dioxide (SiO2)

Limpets Shell / Fossil Specimen

Patellogastropoda (Class)

Chert (specifically Tan/Gray Chert)

Microcrystalline quartz (SiO2)

Chert (varietal: Flint/Jasper)

Silicon Dioxide (SiO2)

Red Slag Glass (Cullet)

Amorphous Silicon Dioxide (SiO2) with metallic dopants

Carved yellow stone butterfly

Undetermined; possibly carved soapstone (talc-rich rock) or another soft ornamental stone

Unidentified gray stone/concrete-like fragment

Indeterminate; likely a fine-grained carbonate or cementitious geological fragment

Polished black obsidian pyramid/block

Obsidian — natural volcanic glass, chiefly rhyolitic silica (approximately 70–75% SiO₂)

Likely chert (flint)

Microcrystalline quartz (SiO₂), likely chert; exact identification is uncertain from the image alone

Amber

Succinates (Organic compound: C10H16O)

Pink Granite

Phaneritic Felsic Igneous Rock (Granite)

Tumbled fossil shark tooth pendant

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

Obsidian (likely Apache tear or flaked obsidian)

Volcanic glass; primarily rhyolitic silica glass (SiO₂-rich, non-crystalline)

Gemstone ring (stones not reliably identifiable from the image)

Likely faceted yellow stones and clear stones set in a metal band; species and treatments are indeterminate visually

Obsidian (likely black obsidian)

Volcanic glass, predominantly rhyolitic to dacitic silica-rich melt; approximate composition ~70–75% SiO₂

Diamond

Native Carbon (C)

Green Opal (Prase Opal)

SiO2 · nH2O (Hydrated Silicon Dioxide)

Weathered concrete or cementitious slab (not natural rock)

Artificial calcium-silicate cement composite; likely Portland cement concrete

Diamond

Carbon (C)

Greenstone

Metabasalt / Metavolcanic rock

Chert (Yellow Jasper/Flint)

Silicon Dioxide (SiO2)

Tumbled chalcedony (likely moss or dendritic agate)

Microcrystalline quartz, SiO₂, with iron-oxide inclusions

Chert (Flint)

Silicon Dioxide (SiO2)

Chert

Chert (SiO2)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)