Mineral Like (Natural Glass)

Red corundum (ruby-colored polished crystal)

Corundum, aluminum oxide (Al₂O₃); red color is typically caused by chromium

Yellow Quartz (Citrine or Yellow Jasper)

Silicon Dioxide (SiO2)

Black Obsidian

Obsidian / Amorphous volcanic glass (SiO2)

Clear quartz crystal (likely quartz point/fragment)

Quartz, silicon dioxide (SiO₂)

Sandstone

Arenite (SiO2 principal component)

Grey Quartz (likely Smoky Quartz or Milky Quartz)

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 primarily)

Aura Quartz (Titanium-coated Quartz)

Silicon Dioxide (SiO2) with metallic vapor coating

Green glassy gemstone-like specimen

Likely synthetic glass or treated quartz; exact identification requires testing

Sandstone with Iron Staining

Arenite (SiO2 with Fe2O3)

Citrine Quartz

Silicon Dioxide (SiO2) with trace Iron

Weathered brown stone, likely chert or iron-stained quartzite

Microcrystalline quartz (SiO₂), probable chert; identification is limited by the image

Synthetic Sapphire and Ion-X Glass

Single-crystal Alumina (Al2O3) and Ion-strengthened Aluminosilicate Glass

Decorative opal-like turtle mosaic

Likely imitation or assembled opal material; exact stones cannot be confirmed visually

Fire Agate (Crackle Agate)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Milky and Smoky Quartz Cobble

Silicon Dioxide (SiO2)

Tumbled green aventurine (probable)

Quartz aggregate, SiO₂, commonly containing fuchsite mica inclusions

Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2AlSi3O10(OH,F)2)

Cullet (Slag Glass)

Amorphous Silica (SiO2) with various metal oxide colorants

Yellow Quartz (Citrine/Yellow Jasper mix)

Silicon Dioxide (SiO2)

Tumbled dark purple quartz, likely amethyst

Quartz (SiO₂), purple variety amethyst; possibly iron-bearing quartz with surface sparkle

Blue-dyed Quartz Druzy

Silicon Dioxide (SiO2) with artificial pigment

Mahogany Obsidian

Obsidian with Hematite inclusions (SiO2 + Fe2O3)

Smoky Quartz

Smoky Quartz (SiO2)

Amethyst (faceted gemstone)

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron-related defects

Sandstone

Arenite (primarily SiO2)

Blue Topaz

Al2SiO4(F,OH)2 (Aluminum silicate fluoride hydroxide)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with iron oxide cement)

Diamond (Faceted)

Carbon (C)

Tumbled amethyst

Quartz, purple variety; silicon dioxide (SiO₂), colored mainly by iron impurities and irradiation

Sandstone

Arenite (compositionally various, primarily SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Amethyst bead bracelet

Quartz, SiO₂; purple variety colored mainly by iron-related defects and irradiation

Green Druzy Quartz (Prasiolite)

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

Sandstone (likely Arkosic or Quartzose)

Arenite (SiO2 based with mineral inclusions)

Amethyst crystal (likely quartz)

Quartz, crystalline silica (SiO₂), purple variety amethyst

Quartz Pebble

Silicon Dioxide (SiO2)

Goldstone and Aura Quartz

Cuprous Glass (Goldstone) and Titanium-coated SiO2 (Aura Quartz)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Polished ocean jasper / orbicular jasper

Microcrystalline quartz (SiO₂), commonly with chalcedony, feldspar, and iron/manganese oxides

Red Sandstone

Arenite (Ferruginous Sandstone)

Tumbled black stone, likely black obsidian

Obsidian — natural volcanic glass, primarily SiO₂