Tektite (Natural Glass)

Clear Quartz

Silicon Dioxide (SiO2)

Slag Glass (Leland Blue variant)

Anthropogenic Vitreous Silicate

Green Druzy Quartz (Prasiolite)

Silicon Dioxide (SiO2) with inclusions (typically Chlorite or Actinolite)

Tumbled jasper, likely red jasper

Microcrystalline quartz (SiO₂), chalcedony variety with iron-oxide impurities

Black Opal (Triplet)

Hydrated Silica (SiO2·nH2O)

Smoky Quartz

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Amethyst

Silicon Dioxide (SiO2) with Iron impurities

Black Spinel

Magnesium Aluminum Oxide (MgAl2O4)

Quartzite

Quartzite (primarily SiO2)

Small polished pink-and-white mineral pebble

Likely rose quartz or pale pink quartz; exact identification is uncertain from the image

Black Onyx

Silicon Dioxide (SiO2) - Chalcedony variant

Polished dark stone, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine

Polished brown jasper (likely ocean or brecciated jasper)

Microcrystalline quartz/chalcedony, SiO₂, colored mainly by iron oxides

Aventurine (likely Green Aventurine)

Silicon Dioxide (SiO2) with various inclusions

Rose quartz beads

Quartz, silicon dioxide (SiO₂), pink variety

Amethyst

Amethyst (Silicon Dioxide - SiO2 with impurities of Fe3+)

Milky Quartz

Silicon Dioxide (SiO2)

Rough Corundum (likely Sapphire or Common Corundum)

Aluminum oxide (Al2O3)

Fluorite (Rainbow Fluorite)

Calcium Fluoride (CaF2)

Banded Agate (Onyx type)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Citrine Geode (or Druzy Citrine)

Silicon Dioxide (SiO₂) - a variety of Quartz

Sandstone

Arenite (general term for sandstone)

Quartz (Rock Crystal)

Quartz (SiO₂ - Silicon Dioxide)

Dark volcanic sand / basaltic sand

Basalt-derived lithic sand, chiefly plagioclase, pyroxene, and volcanic glass

Red Coral (Precious Coral)

Corallium rubrum (Calcium Carbonate, CaCO3)

Red Jasper

SiO2 (Microcrystalline Quartz)

Tumbled yellow-brown translucent stones, likely quartz/chalcedony

Quartz (SiO₂) or microcrystalline quartz (chalcedony); exact identification requires testing

Smoky Quartz in Matrix (Pegmatite)

Silicon Dioxide (SiO2) with Potassium Feldspar and Biotite mica

Druzy Quartz

Quartz (Silicon Dioxide, SiO2)

Green cabochon gemstone, likely aventurine or dyed chalcedony

Indeterminate from image; possible quartz variety (SiO₂), including aventurine quartz or chalcedony

Vesicular volcanic scoria (likely weathered basaltic scoria)

Scoria; chiefly vesicular basalt, composed mainly of plagioclase, pyroxene, and iron-rich glass

Pink quartz beads (likely rose quartz)

Quartz, SiO₂; pink color commonly from trace inclusions or lattice defects

Quartzite

Quartzite

Green Aventurine

Aventurine (a variety of Quartz, SiO2)

Quartz (likely) or a Quartzite Pebble

Silicon dioxide (SiO2) for quartz. If it's quartzite, it's a metamorphic rock primarily composed of quartz.

Glauconitic Sandstone (or Greensand)

Glauconitic Siliciclastic Rock (Containing (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Lapis lazuli and green-blue chalcedony jewelry

Lapis lazuli: lazurite-bearing metamorphic rock, chiefly lazurite (Na₃Ca(Al₃Si₃O₁₂)S) with calcite and pyrite; second stone: likely chrysoprase or green-blue chalcedony (microcrystalline quartz, SiO₂)

Sandstone

Quartz Arenite (a type of sandstone composed of more than 90% quartz)

Flint

SiO2 (Microcrystalline Quartz)

Pearls

Pearl: biomineralized aragonite (CaCO₃) and conchiolin