Opal
Hydrated Silica (SiO2·nH2O)
Category
Browse sedimentary (formed from silica deposits) specimens identified by the Rock Identifier community.
Opal
Hydrated Silica (SiO2·nH2O)
Selenite (gypsum)
Gypsum, CaSO₄·2H₂O; transparent or translucent variety commonly called selenite
Chert (Flint) with Limestone Matrix
Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)
Chert (specifically Flint or Common Opal fragment)
Cryptocrystalline Silica (SiO2)
Crazy Lace Agate
Silicon Dioxide (SiO2)
Jasper (likely Brown or Brecciated)
Jasper (Silicon Dioxide, SiO2)
Chert (Flint)
Cryptocrystalline Quartz (SiO2)
Chert (Jasper) pebble
Microcrystalline Quartz (SiO2)
Red Jasper
Silicon Dioxide (SiO2)
Chert (Iron-rich or Jasperoid)
Cryptocrystalline Quartz (SiO2)
Chert (Arrowhead Fragment)
Cryptocrystalline quartz (SiO2)
Quartz-rich chalcedony (likely silicified rock)
Microcrystalline quartz, SiO₂; possibly silicified limestone or jasper
Jasper
Jasper (Silicon Dioxide, SiO2)
Red Moss Agate or Jasper-Agate
Silicon Dioxide (SiO2)
Clear Quartz (Rock Crystal)
Quartz (Silicon Dioxide, SiO2)
Tumbled Jasper
Silicon dioxide with impurities (Microcrystalline Quartz, SiO2)
Jasper (Chert / Chalcedony)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
Jasper
Silicon Dioxide (SiO2)
Chalcedony (Agate / Chert)
Silicon Dioxide (SiO2)
Jasper
Microcrystalline Quartz (SiO2)
Chert (often called Flint in dark varieties)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Fossilized shell fragment
Indeterminate fossil mollusk; likely a silicified or mineral-replaced bivalve/gastropod fragment
Chert Pebble
Microcrystalline quartz (SiO2)
Chert (specifically Jasper/Flint)
Microcrystalline Quartz (SiO2)
Carnelian (Chalcedony)
Silicon Dioxide (SiO2)
Red Jasper
Microcrystalline Quartz (Chalcedony), SiO2
Silicified fossil shell, likely fossil oyster or clam
Silicified bivalve fossil; shell originally aragonite/calcite, partly replaced by chalcedony (SiO₂)
Amethyst Geode
Silicon Dioxide (SiO2) with iron impurities
Jasper
Jasper (Silicon Dioxide, SiO2)
Jasper
Microcrystalline Quartz (SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Green Jasper
Silicon Dioxide (SiO2) with impurities
Chert (Flint)
Chert (SiO2)
Chert (Quartz Variety)
Silicon Dioxide (SiO2)
Agate Nodules
Cryptocrystalline Quartz (SiO2)
Carnelian (Tumbled)
Silicon Dioxide (SiO2)
Chert (Chalcedony/Agate variety)
Microcrystalline Quartz (SiO2)
Jasper
Silicon dioxide (SiO2)
Banded Chert
Chert (Silicon Dioxide, SiO2)
Chert (Flint)
Silicon Dioxide (SiO2)
Weathered chert or siliceous limestone
Microcrystalline quartz (SiO₂), possibly with carbonate minerals
Jasper with Hematite inclusions
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3)