Snowflake Obsidian
Obsidian with Cristobalite inclusions (70-75% SiO2)
igneous
Category
Mineral Like (Natural Glass)
Browse mineral like (natural glass) specimens identified by the Rock Identifier community.
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Polished black obsidian
Volcanic glass; primarily silica-rich rhyolitic composition (SiO₂)
igneous
Sandstone (Ferruginous)
Arenite (with Hematite/Limonite cement)
sedimentary
Bull Quartz with Mica and Host Rock
Massive Quartz (SiO2) with Muscovite/Chlorite inclusions
igneous
Blue Topaz
Aluminum silicate fluoride hydroxide (Al2SiO4(F,OH)2)
mineral
Chert (Yellow Jasper)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Chert (Vuggy or Weathered)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Goldstone (aventurine glass)
Synthetic copper-bearing soda-lime glass; commonly sold as red goldstone
gemstone
Sandstone
Arenite (SiO2 secondary)
sedimentary
Sandstone (likely Greywacke or Siltstone variety)
Arenite / Siltstone (primarily SiO2)
sedimentary
Citrine Quartz
SiO2 (Silicon Dioxide with Iron impurities)
mineral
Yellow Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Slag Glass
Amorphous Silica Glass (with metal oxide inclusions)
Mineraloid / Industrial Waste
Citrine (Heat-Treated)
Silicon Dioxide (SiO2)
mineral
Adventurine (Green)
Silicon Dioxide (SiO2) with inclusions of Fuchsite
metamorphic
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Smoky Quartz / Agate Pebbles
Silicon Dioxide (SiO2)
mineral
Herkimer Diamond
Quartz (Silicon Dioxide) - SiO2
mineral
Agate Slices and Clear Quartz Points
Agate (SiO2 Chalcedony) and Clear Quartz (SiO2 Crystalline)
mineral
Sandstone
Sedimentary Rock (Quartz Sandstone)
sedimentary
Amethyst (Chevron or Banded Amethyst)
Silicon Dioxide (SiO2 with iron impurities)
Mineral
Banded Chert / Cryptocrystalline Quartz
Silicon Dioxide (SiO2)
sedimentary
Tumbled green aventurine (probable), with blue-gray tumbled stones
Aventurine quartz, SiO₂ with fuchsite or other mica inclusions; blue stones may be sodalite or dyed quartz
mineral
Quartz (Citrine variety)
Silicon Dioxide (SiO2)
mineral
Green Slag Glass
Amorphous Silica Glass (Anthropogenic)
Industrial byproduct (often mistaken for obsidian or mineral)
Yellow Quartz (Citrine Quartz / Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Blue Goldstone
Aventurine glass (Synthetic borosilicate glass with cobalt and metallic inclusions)
man-made glass
Amethyst-bearing quartz
Quartz, silicon dioxide (SiO₂), purple variety amethyst
mineral
Sandstone
Arenite (principally SiO2)
sedimentary
Sandstone (Quartz Arenite)
Sandstone (SiO2 with possible mineral cements)
sedimentary
Ruby (Faceted)
Corundum (Al2O3:Cr)
gemstone
Sandstone
Arenite (primarily SiO2)
sedimentary
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
River Stone (likely Mudstone or Siltstone)
Lutite (Clastic sedimentary rock composed of clay and silt-sized particles)
sedimentary
Likely clear quartz crystal or glass-like gemstone
Quartz, silicon dioxide (SiO₂); exact identification is uncertain from the strongly magenta-lit image
mineral
Green aventurine bead bracelet
Quartz (SiO₂), typically green aventurine containing fuchsite mica or other chromium-bearing inclusions
mineral
Chalcedony (Agate / Jasper Pebble)
Silicon Dioxide (SiO2)
mineral
Citrine
Silicon Dioxide (SiO2) with iron impurities
Mineral
Yellow Quartz (Citrine Quartz)
Silicon Dioxide (SiO2)
mineral
Chert
Microcrystalline Quartz (SiO2)
sedimentary