Obsidian
Obsidian (Amorphous volcanic glass, SiO2 rich)
Category
Browse mineral (specifically a variety of chalcedony, which is microcrystalline quartz) specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Amorphous volcanic glass, SiO2 rich)
Quartz (Milky Quartz / Greenish Quartz)
SiO2 (Silicon Dioxide)
Green Moss Agate
Agate (Silicon Dioxide - SiO2 with inclusions of Manganese/Iron oxides)
Chalcedony (Carnelian variety)
Silicon Dioxide (SiO2)
White Quartz
Silicon Dioxide (SiO2)
Chert (Nodular or Massive Variety)
Cryptocrystalline Quartz (SiO2)
Iridescent Ammonite
Ammonoidea (Species: likely Cleoniceras or Desmoceras); Mineral: Aragonite/Ammolite (CaCO3)
Milky Quartz
Silicon Dioxide (SiO2)
Quartz
Quartz (SiO2 - Silicon Dioxide)
Chert (specifically Iron-stained River Cobble)
Silicon Dioxide (SiO2)
Blue Chalcedony
Chalcedony (Silicon Dioxide, SiO2)
Agate Geode
Silicon Dioxide (SiO2)
Chert (and/or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Quartz
Silicon Dioxide (SiO2)
Banded Chert
Microcrystalline Quartz (SiO2)
Quartz
Silicon Dioxide (SiO2)
Orthoclase Feldspar (or K-Feldspar)
Orthoclase (KAlSi3O8)
Quartzite Pebble
Metamorphic Quartzite (SiO2)
Quartz (Vein Quartz)
Silicon Dioxide (SiO2)
Aventurine (likely Green Aventurine)
Silicon Dioxide (SiO2) with various inclusions
Citrine Quartz
Silicon Dioxide (SiO2)
Quartz / Quartz Geode fragment
Silicon Dioxide (SiO2)
Quartz
Silicon dioxide (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Ocean Jasper (Orbicular Jasper)
Spherulitic Chalcedony/Rhyolite (SiO2)
Chert (often called Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Agate
Silicon Dioxide (SiO2)
Dendritic Agate
Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions
Pink Quartzite
Quartzite (primarily SiO2)
Turquoise
Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]
Quartz Crystal (specifically Rock Crystal)
Silicon Dioxide (SiO2)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
White Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
Quartz
Silicon Dioxide (SiO₂)
Quartzite
Quartzite (primarily SiO2)
Agate (Chalcedony)
Cryptocrystalline Silica or Silicon Dioxide (SiO2)
Yellow Quartz
Silicon Dioxide (SiO2)
White Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
Milky Quartz
Silicon Dioxide (SiO2)
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Milky Quartz
Quartz (Silicon Dioxide - SiO2)