Black Freshwater Pearls
Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3
Category
Browse organic (pseudo geological) specimens identified by the Rock Identifier community.
Black Freshwater Pearls
Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3
Jasper
Silicon Dioxide (SiO2) with impurities
Chert (Jasper variation)
Silicon Dioxide (SiO2)
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
Chert (Smooth River Pebble)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Chalcopyrite
CuFeS2
Glauconitic Sandstone
Glauconitic Quartz Arenite
Chert (specifically Flint or Jasper variant)
Microcrystalline quartz (SiO2)
Chert
Microcrystalline Quartz (SiO2)
Chert
Cryptocrystalline Quartz (SiO2)
Desert Rose Fragment (Atypical) / Weathered Chert
Silicon Dioxide (SiO2) or Barium Sulfate (BaSO4) depending on exact mineralogy
Limestone with Fossil Fragment
Sedimentary carbonate rock (CaCO3)
Ambergris (Geological/Organic Specimen)
Ambra grisea (Produced by Physeter macrocephalus)
Fossiliferous Limestone
Biogenic Sedimentary Rock (CaCO3)
Petrified Wood
Silicified Wood (primarily Quartz / Chalcedony: SiO2)
Limestone
Calcium Carbonate (CaCO3)
Limestone
Calcium Carbonate (CaCO3)
Petrified Wood
Silicified wood (SiO2)
Fossilized Plant or Tree Bark
Lepidodendron or Sigillaria (example genera)
Likely bituminous coal
Coal, predominantly carbon-rich organic matter with variable maceral and mineral content
Grass (Organic Matter/Soil)
Poaceae (family of monocotyledonous flowering plants)
Chert (Jasper/Flint variant)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Chert (Jasper)
Microcrystalline Quartz (SiO2)
Chert (variations include Flint)
Silicon Dioxide (SiO2)
Sandstone
Arenite
Black Jasper (Etched)
Silicon Dioxide (SiO2) with impurities
Chert (Flint)
Microcrystalline Quartz (SiO2)
Chert (Flint)
Silicon Dioxide (SiO2)
Chert with Limestone matrix
Microcrystalline silica (SiO2) in Calcite (CaCO3) matrix
Fossiliferous Rock (Invertebrate Fossil in Matrix)
Fossiliferous limestone or shaly matrix containing skeletal fossil remains
Chert (Flint variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Jasper
Microcrystalline Quartz (SiO2)
Jasper
Silicon Dioxide (Microcrystalline Quartz, SiO2)
Jasper
Silicon dioxide (SiO2)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Petrified Wood
Silicified wood (SiO2)
Pink Coral
Corallium rubrum (or related species, composed of calcium carbonate)
Fossiliferous Kalkstein (Marl/Sandstone)
Fossiliferous calcarenite/siltstone
Siderite Concretion in Shale
Iron carbonate (FeCO3) in Mudstone/Shale matrix
Polished moss agate (likely)
Chalcedony, microcrystalline quartz (SiO₂), with dark mineral inclusions
Fossilized Bivalve
Phylum Mollusca
Agate with Fossil Bone
Silicified bone in Chalcedony (SiO2)