Mineraloid (Human Made Geological Specimen)

Ironstone Concretion (Pot Stone)

Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)

Obsidian

Obsidian (Amorphous volcanic glass, SiO2 with impurities)

Black Obsidian

Volcanic Glass (SiO2)

Obsidian

Obsidian (Volcanic Glass), primarily SiO2

Mixed gemstone jewelry collection

Various gemstone minerals, including likely amethyst (quartz), sapphire or iolite, garnet, pearl, turquoise, and colored beryl or tourmaline

Snowflake Obsidian

Volcanic Glass with Spherulite inclusions (Chemical composition: 70–75% SiO2 + MgO, Fe3O4)

Faceted colorless gemstone, likely quartz or glass imitation

Most plausibly rock crystal (quartz, SiO₂); identity is uncertain because the photograph shows only intense facet reflections

Chert (Flint)

Chert (Microcrystalline or cryptocrystalline Quartz - SiO2)

Jasper

Silicon Dioxide (Quartz variety, SiO2)

Granite Pebble

Phaneritic plutonic rock (SiO2 primary)

Slag

Glassy silicate byproduct (anthropogenic material)

Chert / Yellow Jasper

Microcrystalline Quartz (SiO2)

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Polished star-shaped gemstone, likely black obsidian

Obsidian (volcanic glass), predominantly SiO₂

Tumbled green stone, likely serpentine or aventurine

Probable serpentine-group mineral (Mg₃Si₂O₅(OH)₄) or green aventurine quartz (SiO₂)

Chert Arrowhead

Microcrystalline Quartz (SiO2)

Tumbled hematite (likely hematite-rich iron oxide)

Hematite, Fe₂O₃; possibly mixed with magnetite, Fe₃O₄

Tumbled amethyst quartz point

Amethyst, purple quartz (SiO₂)

Flint Arrowhead

Cryptocrystalline quartz (Chert/Flint, SiO2)

Quartz crystal pendant (likely smoky quartz or iron-stained quartz)

Quartz, silicon dioxide (SiO₂)

Tumbled black stone, likely obsidian

Obsidian — volcanic glass, chiefly silica-rich rhyolitic composition

Vesicular volcanic rock, likely pumice

Pumice (highly vesicular volcanic glass; composition commonly rhyolitic to andesitic)

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Gray Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Brain Coral Fossil

Family Mussidae or Merulinidae (Order Scleractinia)

Obsidian (likely black obsidian)

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

Tumbled chalcedony (likely carnelian or mossy agate)

Microcrystalline quartz, SiO₂; chalcedony variety, possibly iron-stained carnelian

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Likely obsidian (rough fragment)

Volcanic glass, predominantly silica-rich rhyolitic composition (SiO₂-rich, noncrystalline)

Carved translucent jade pendant

Likely nephrite jade (actinolite–tremolite series); possibly jadeite or chalcedony, identification requires testing

Black Obsidian

Volcanic glass (Amorphous silicates)

Green jade or aventurine bead bracelet

Most likely nephrite jade (aggregated amphibole, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂) or green aventurine (quartz, SiO₂); exact identification requires testing

Green faceted bead strand, likely dyed or synthetic material

Uncertain; possibly green-dyed quartz, glass, or lab-created emerald-like material

Tumbled quartz-rich pebble, possibly smoky quartz or chert

Quartz (SiO₂), or microcrystalline quartz if chert

Green aventurine and gray stone pendant

Likely green aventurine quartz (SiO₂), paired with a gray quartzite or feldspar-rich stone; exact identification requires testing

Blue Agate (Dyed Chalcedony)

Silicon Dioxide (SiO2)

Cullet Glass (Strawberry Glass)

Amorphous Silicon Dioxide (SiO2) with metallic dopants

Kidney Stone

Calcium Oxalate (CaC2O4), Uric Acid, or Struvite

Tumbled green stone, likely serpentine or green jasper

Probable serpentine-group mineral (Mg₃Si₂O₅(OH)₄) or microcrystalline quartz/chalcedony

Tumbled tan stone, likely quartzite or jasper

Quartz-rich quartzite (SiO₂) or opaque jasper (microcrystalline quartz)

Chert (Jasper/Flint variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Obsidian

Volcanic glass (Amorphous silicon dioxide)