Shale
Shale (comprised mostly of clay minerals and quartz)
Category
Browse organic gemstone (sedimentary classification) specimens identified by the Rock Identifier community.
Shale
Shale (comprised mostly of clay minerals and quartz)
Shale
Fissile Mudstone (Shale)
Amber Chert (Jasper)
Microcrystalline Quartz (SiO2)
Chert (Chalcedony/Flint)
Silicon Dioxide (SiO2)
Shungite
Non-crystalline carbon (high-carbon metamorphic rock)
Pyrite
Iron Sulfide (FeS2)
Chert (Nodule)
Cryptocrystalline Quartz (SiO2)
Flint
Chert (Silicon dioxide, SiO2)
Chert (Arrowhead variety)
Chert (SiO2)
Chert (Jasper variety)
Microcrystalline Quartz (SiO2)
Amber
Succinite (Formula: C10H16O)
Chert (Jasper variety)
Microcrystalline Quartz (SiO2)
Natural Pearl (appearing in a jewelry setting)
Calcium Carbonate (mostly Aragonite), CaCO3 with Conchiolin
Fossiliferous Limestone (Shell Fragment)
Biogenic Limestone (Calcium Carbonate / CaCO3)
Fossilized Shell in Limestone
Bivalve fossil (CaCO3) in Carbonate Sedimentary Rock
Chert / Flint
Microcrystalline Quartz (SiO2)
Bituminous Coal
Organic sedimentary rock (humic coal)
Pearl
Calcium Carbonate (CaCO3) - Aragonite/Calcite organic gemstone
Pearl
Organic Mineral (CaCO3 with conchiolin)
Petrified Wood
Silicified Wood (SiO2)
Chert (Jasper variation)
Chert (Microcrystalline Silicon Dioxide, SiO2)
Stromatolite
Biogenic Sedimentary Rock (composed predominantly of CaCO3)
Bituminous Coal
Bituminous coal (Organic Sedimentary Rock)
Amber
Succinite (specifically for Baltic amber); Chemical formula approximately C10H16O
Banded Chert
Sedimentary Cryptocrystalline Quartz (SiO2)
Chert (Beach Pebble)
Microcrystalline Quartz (SiO2)
Chert (Jasper/Flint variant)
Microcrystalline Quartz (SiO2)
Sandstone
Arenite
Agatized Fossil (Druzy Agate)
Silicon Dioxide (SiO2) replacing organic matter
Chert (Flint)
Microcrystalline Quartz (SiO2)
Jasper
Silicon dioxide (SiO2) with impurities
Pyrite in Matrix (Fool's Gold)
Iron Disulfide (FeS2)
Orange Calcite
Calcium Carbonate (CaCO3)
Fossil Shark Tooth (Sand Tiger or Mackerel Shark)
Carcharias sp. or Otodus sp. replaced by Hydroxylapatite/Calcium Carbonate
Fossiliferous Limestone
Fossiliferous Limestone
Brachiopod Fossil in Limestone
Phylum Brachiopoda (likely Order Spiriferida), CaCO3 (Calcite)
Moss Agate and Hematite
Silica (SiO2) with fibrous inclusions of Manganese or Iron; Hematite (Fe2O3)
Amber
Succinite (fossilized tree resin)
Chert (often called Flint in various colors)
Silicon Dioxide (SiO2)
Graphite
Graphite (Carbon, C)
Graphite
Graphite (Native Carbon), Formula: C
Fossil Coral
Cnidaria Anthozoa (Fossilized)