Siderite Concretion in Shale
Iron carbonate (FeCO3) in Mudstone/Shale matrix
Category
Browse organic gemstone (sedimentary classification) specimens identified by the Rock Identifier community.
Siderite Concretion in Shale
Iron carbonate (FeCO3) in Mudstone/Shale matrix
Quartz-veined Limestone
Sedimentary limestone with quartz/calcite veinlets
Amber
Succinite
Limestone or Sandstone Cobble
Sedimentary rock (Calcium carbonate or Quartz based)
Pearl
Organic Mineral (CaCO3 with conchiolin)
Weathered pink granite cobble
Granite, likely biotite-bearing pink granite; exact variety cannot be confirmed from a photograph
Pearl
Aragonite / Calcium Carbonate (CaCO3)
Pearl oyster shell with cultured pearls
Mollusk shell (likely Pinctada spp.) containing aragonite pearls, CaCO₃
Jasper containing fossilized inclusions
Silicon Dioxide (SiO2) with trace impurities and biogenic inclusions
Moss Agate
Chalcedony (Silicon Dioxide, SiO2) with inclusions
Moss Agate / Chalcedony
Silicon Dioxide (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Pearl
Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3
Petrified Wood
Silicified Wood (SiO2)
Likely bituminous coal
Coal, predominantly carbon-rich organic matter; exact rank cannot be confirmed visually
Fossil Shark Tooth
Carcharodon sp. (likely Otodus or similar Lamniformes order)
Amber
Succinite (fossilized organic resin)
Amber
Succinite (fossilized tree resin)
Soil with Mineral Detritus and Quartz Fragments
Regolith / Silicate Mineral Aggregate
Chert Nodules in Limestone
Cryptocrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
Fossiliferous Limestone / Petrifaction
Sedimentary rock with fossil inclusions / Calcium Carbonate (CaCO3)
Pearl
Pearl; primarily aragonite (CaCO₃) with conchiolin
Fossilized Gastropod / Coral
Phylum Mollusca / Cnidaria (Silicified or Calcified)
Pearl (with Peridot)
Calcium carbonate (CaCO3) + Conchiolin; Peridot: Magnesium iron silicate (Mg, Fe)2SiO4
Banded Jasper
Silicate Mineral (Microcrystalline Quartz / SiO2)
Chert (Flint/Jasper variety)
Microcrystalline Quartz (SiO2)
Jasper
Microcrystalline Quartz (SiO2)
Chert / Jasper
Silicon Dioxide (SiO2)
Graphite
Graphite (Carbon, C)
Jasper
Silicon Dioxide (SiO2) with impurities
Jasper
Microcrystalline quartz (SiO2)
Chert / Flint
Chert (SiO2)
Chert (Flint)
Cryptocrystalline Quartz (SiO2)
Shungite
Non-crystalline carbon (allotrope of carbon)
Amber
Succinite (C10H16O)
Iron-stained quartz-rich cobble, possibly weathered granite or quartz vein rock
Quartz–feldspar aggregate with iron-oxide staining; exact classification is uncertain from the photograph
Likely iron-rich rock or metallic mineral fragment
Uncertain; possibly limonite/goethite-rich material or weathered iron meteorite fragment
Black Pearl (Tahitian-style Cultured Pearl)
Calcium Carbonate (Aragonite) with Conchiolin (CaCO3)
Amber
Succinite (approximate formula C10H16O)
Polished amber-like agate or jasper carving
Likely chalcedony (microcrystalline SiO₂), possibly iron-stained carnelian/jasper; exact identification requires testing
Coal
Bituminous Coal (organic sedimentary rock)
Bituminous Coal
Bituminous coal (Organic Sedimentary Rock)