Common Opal
Hydrated amorphous form of silica (SiO2·nH2O)
Category
Browse synthetic (glass) specimens identified by the Rock Identifier community.
Common Opal
Hydrated amorphous form of silica (SiO2·nH2O)
Red Coral
Corallium rubrum
Banded Calcite (Mexican Onyx)
Calcite (Calcium Carbonate, CaCO3)
Ferruginous Chert
Microcrystalline Quartz (SiO2) with Iron Oxides
Riverstone Quartzite
Quartzite (primarily SiO2)
Quartz
Silicon Dioxide (SiO2)
Basalt
Basalt
Quartz (Smoky/Milky Pebble)
Silicon Dioxide (SiO2)
Chert (Arrowhead Fragment)
Microcrystalline Quartz (SiO2)
Obsidian
Volcanic Glass (SiO2 - Silicon Dioxide with impurities)
Yellow Quartzite (River Cobble)
Quartzite (SiO2)
Chert (Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Quartz (Microcrystalline/Chert)
Silicon Dioxide (SiO2)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Red Quartzite
Quartzite (primarily SiO2)
Orthoclase Feldspar
KAlSi3O8 (Potassium aluminum silicate)
Clear Quartz Cluster
Silicon Dioxide (SiO2)
Quartz (Milky or Smoky Quartz)
Silicon Dioxide (SiO2)
Quartzite Pebble (with Iron Staining)
Quartzite (mainly SiO2)
Quartzite
Quartzite (Primary mineral: SiO2)
Quartzite
Quartzite (primarily SiO2)
Quartzite Pebble
Quartzite (SiO2)
Chert (Iron-stained)
Microcrystalline silica (SiO2) with trace Iron oxide (Fe2O3)
Iron-stained Quartzite / Chert
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
Mica Schist
Mica Schist (primarily Muscovite or Biotite KAl2(AlSi3O10)(OH)2)
Aventurine
Silicon Dioxide (Quartz with Fuchsite inclusions) - SiO2
Green Aventurine
Quartz (SiO2) containing Fuchsite (K(Al,Cr)2(AlSi3O10)(OH)2)
Quartzite (Pebble)
Quartzite
Green Aventurine
Silicon Dioxide with Fuchsite (SiO2 + K(Al,Cr)2AlSi3O10(OH)2)
Green Aventurine
Silicon Dioxide (SiO2) with Fuchsite inclusions
Pink Quartzite
Quartzite (SiO2)
Chert (and Flint variant)
Microcrystalline Quartz (SiO2)
Muscovite (White Mica)
Muscovite - Potassium aluminum silicate: KAl2(AlSi3O10)(F,OH)2
Quartzite
Quartzite (SiO2)
Quartzite
Quartzite (SiO2)
Quartzite
Quartzite (SiO2)
Mica (specimen appears to be Muscovite or Phlogopite)
Phyllosilicate mineral; Muscovite: KAl2(AlSi3O10)(F,OH)2
Quartzite
Quartzite (SiO2)
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
Quartzite
Quartzite (SiO2)
Quartzite (River Pebble)
Metamorphosed Quartz Sandstone (primarily SiO2)
Chert (often called Flint or River Rock)
Microcrystalline or Cryptocrystalline Quartz (SiO2)