Chert (Iron-Stained)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Category
Organic Gemstone
Browse organic gemstone specimens identified by the Rock Identifier community.
Cat's Eye Moonstone (Feldspar)
Orthoclase (KAlSi3O8) with Albite (NaAlSi3O8) inclusions
mineral
Moss Agate
Chalcedony (Silicon Dioxide with inclusions) - SiO2
mineral
Peridot (Olivine)
Magnesium Iron Silicate (Mg,Fe)2SiO4
mineral
Moonstone
Orthoclase (Potassium Aluminum Silicate), Formula: (K,Na)AlSi3O8
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Fossilized Wood (with Coal and Limonite)
Petrified Wood (Silicified or Carbonized Flora)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
mineral
Chert (Green variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Petrified Wood (Agatized/Silicified Wood)
Silicified Wood / Chalcedony (SiO2)
sedimentary
Chert (Iron-stained)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Chert (Cryptocrystalline variety of Quartz, SiO2)
sedimentary
Olivine (Peridotite)
Magnesium iron silicate (Mg, Fe)2SiO4
igneous
Cubic Zirconia (CZ)
Zirconium dioxide (ZrO2)
mineral
Shale with Vein Infillings
Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.
Sedimentary Rock
Pearl
Aragonite (CaCO3) with Conchiolin
mineral
Emerald in Host Rock
Beryl (Be3Al2Si6O18) containing Chromium and/or Vanadium
mineral
Ironstone Concretion (Limonite/Hematite Nodules)
Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)
sedimentary
Jasper (Petrified Wood variant)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Stromatolite (Jasper-replaced)
Fossilized Stromatolite (Cyanobacteria / Cryptozon / Silica SiO2)
sedimentary
Grey and White Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2) within a secondary sedimentary structure
sedimentary
Petrified Wood
Silicified Wood (SiO2)
metamorphic
Chert (Quartz Variety)
Microcrystalline Silica (SiO2)
sedimentary
Chert (Flint Pebbles)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Rhodonite
Manganese silicate (Mn,Fe,Mg,Ca)SiO3
mineral
Moonstone (Feldspar)
Orthoclase feldspar, (K,Na)AlSi3O8
mineral
Citrine Quartz
Silicon Dioxide (SiO2) with iron impurities
mineral
Banded Agate (Gray Agate)
Silicon Dioxide (SiO2) - Chalcedony
mineral
Black Sapphire
Corundum (Al2O3)
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Chert (Smooth River Pebble)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Graphite-veined Quartzite
Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)
metamorphic
Jasper with Quartz Vein
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Fossil Coral (Favosites Honeycomb)
Favosites (Genus), Phylum Cnidaria, Class Anthozoa
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Jasper (Iron-stained Chert)
Silicon Dioxide (SiO2) with impurities of Hematite or Goethite
sedimentary
Emerald in Matrix
Beryl (Be3Al2Si6O18) with trace amounts of Chromium/Vanadium
mineral
Olivine (Peridot)
Magnesium Iron Silicate (Mg,Fe)2SiO4
Mineral
Moonstone
Orthoclase (KAlSi3O8) or Albite (NaAlSi3O8)
mineral