Mineraloid (Human Made Geological Specimen)

Green Glass (often marketed as 'Obsidian' or 'Green Quartz')

Amorphous Silica (SiO2) with copper or chromium additives

Blue opal heart cabochon

Common opal, hydrated amorphous silica (SiO₂·nH₂O), likely blue-dyed or synthetic opalite

Amber

Succinite (fossilized resin); C10H16O

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Natural White Pearl

Calcium Carbonate (Aragonite/Calcite) with Conchiolin - CaCO3

Tumbled brown banded jasper

Microcrystalline quartz (SiO₂), commonly chalcedony with iron-oxide inclusions

Goldstone (Brown/Gold)

Aventurine Glass (Man-made glass with Copper inclusions)

Flint or chert flake

Microcrystalline quartz (SiO₂), commonly chalcedony with possible impurities

Granite Pebble

Felsic intrusive igneous rock

Obsidian Arrowhead

Volcanic Glass (predominantly SiO2)

Tumbled green aventurine (probable)

Quartz, SiO₂, with green fuchsite mica inclusions

Banded sandstone pebble

Lithic or quartz-rich sandstone; exact composition requires testing

Polished/tumbled brown jasper (likely weathered chert)

Microcrystalline quartz, SiO₂, with iron-oxide impurities

Tumbled black obsidian (likely)

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

Obsidian

Volcanic Glass (SiO2)

Mixed Mineral Collection (with Titanium Aura Quartz)

Silicon Dioxide (SiO2) with metallic coatings and various silicates

Polished black stone pendant

Likely black obsidian or black tourmaline; exact identification is uncertain from the photograph

Limonite (Iron Ore)

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

White quartz pebble

Quartz (silicon dioxide, SiO₂), likely milky quartz

Tumbled beige stone, possibly quartz or calcite

Indeterminate from photograph; likely microcrystalline quartz (SiO₂) or calcite (CaCO₃)

Blue glassy fragment among beach gravel

Likely cobalt-blue man-made glass; not a natural mineral specimen

Human Skin (Epidermis/Dermis)

Integumentary tissue (High content of hydroxyapatite in bones, though the surface is biological)

Gold Sheen Obsidian

Volcanic Glass (SiO2 + Fe3O4 / Gas Inclusions)

Yellow Chert (Chalcedony)

Microcrystalline Quartz (SiO2)

Jasper Pebble

Microcrystalline Quartz (SiO2)

Black Obsidian

Volcanic Glass (Amorphous Silicon Dioxide)

Polished blue stone, likely sodalite or dyed agate

Sodalite: Na₈(Al₆Si₆O₂₄)Cl₂; exact identification requires testing

Obsidian (likely snowflake-free black variety)

Volcanic glass; primarily SiO₂-rich rhyolitic composition

Weathered basalt column

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase, pyroxene, and commonly olivine

Blue Opal Inlay (Simulated/Lab-created)

Hydrated Amorphous Silica (SiO2·nH2O) with polymer resin

Clear quartz sphere or polished quartz cabochon (tentative)

Quartz, silicon dioxide (SiO₂); appearance may also be consistent with ordinary glass, which cannot be ruled out from the image alone

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Faceted clear gemstone, likely quartz or glass imitation

Most likely quartz (SiO₂); exact identification requires refractive-index and hardness tests

Obsidian

Obsidian (Volcanic Glass)

Common Opal (Green Opal / Pistachio Opal)

Hydrated silica (SiO2·nH2O)

Rounded quartz pebble

Quartz (silicon dioxide, SiO₂)

Tumbled greenstone (likely serpentine or nephrite-like material)

Serpentine-group minerals, commonly antigorite/lizardite; possibly nephrite jade (actinolite-tremolite)

Pink opal

Common opal, hydrated amorphous silica (SiO₂·nH₂O), commonly colored by trace organic or iron compounds

Black obsidian

Volcanic glass; predominantly rhyolitic silica-rich melt (approximately 70–80% SiO₂), lacking crystalline structure

Common Opal (Potch)

Hydrated Silica (SiO2·nH2O)

Pyrite

Iron Sulfide (FeS2)

Man-made Glass (Tumbled/Shaped)

Amorphous Silicon Dioxide (SiO2) with metal oxide colorants