Anthracite Coal
Carbon (with organic impurities)
sedimentary
Category
Organic (Mineraloid)
Browse organic (mineraloid) specimens identified by the Rock Identifier community.
Learn about Organic (Mineraloid) in the encyclopedia
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Amber
Organic gemstone (Succinite)
mineral
Amber
Succinates (Organic Gemstone)
mineral
Fossilized Shell Fragment
Invertebrate marine fossil, likely calcium carbonate replacement
fossil
Slag (Industrial Glass)
Artificial Vitreous Silicate
mineraloid (anthropogenic)
Sea Glass
Amorphous Silica (SiO2) with various additives
Mineraloid (Anthropogenic)
Opalite
Man-made Glass (SiO2 + additives)
mineraloid (synthetic)
Slag
Ferrous slag (by-product of iron smelting)
Mineraloid / Anthropogenic
Moldavite
Silica glass with small amounts of aluminum, iron, and other elements
Mineraloid / Tektite
Shale or Slate
Shale (Sedimentary) or Slate (Metamorphic)
sedimentary or metamorphic
Fossilized Shell Fragment / Mother of Pearl
Calcium Carbonate (CaCO3) - Aragonite/Calcite biomineral
fossil
Polished black stone egg, probably black obsidian
Obsidian, a natural volcanic glass; composition primarily silica-rich glass (approximately SiO₂), with variable iron and other trace elements
gemstone
Pearl
Calcium Carbonate (CaCO3) with Conchiolin
mineral
Pearl
Calcium Carbonate (Aragonite/Calcite) with Conchiolin
gemstone
Petrified Wood
Silicified Wood (SiO2)
fossil
Weathered Sedimentary Rock
Sedimentary Rock
Sedimentary
Pearl
Calcium carbonate (CaCO3) as Aragonite or Calcite
mineral
Fossiliferous Sandstone
Sedimentary rock containing invertebrate fossils
fossil
Chert (Green and Black Jasper variant)
Cryptocrystalline Quartz (SiO2)
sedimentary
Limestone or Sandstone Cobble
Sedimentary rock (Calcium carbonate or Quartz based)
sedimentary
Likely bituminous coal
Coal, predominantly carbon-rich organic matter; exact rank cannot be confirmed from the image
sedimentary
Graphite-rich metamorphic rock (graphitic schist)
Graphitic schist; chiefly graphite (C), quartz (SiO₂), and mica minerals
metamorphic
Obsidian
Obsidian (volcanic glass)
Igneous
Tahitian Pearl (Black / Pistachio Pearl)
Biogenic Aragonite / Calcite (CaCO3 with conchiolin)
gemstone
Pearl necklace
Pearl, primarily aragonite (CaCO₃) and conchiolin
gemstone
Kidney Stone
Calcium Oxalate (CaC2O4), Uric Acid, or Struvite
mineral
Amber
Succinite (C10H16O)
mineral
Polished amber
Fossilized tree resin (primarily organic polymerized diterpenes)
gemstone
Petrified Bone (Fossil Bone)
Per mineralization fossil bone (varies by organism, predominantly replacement by SiO2 - Quartz/Chalcedony)
fossil
Petrified Wood / Fossilized Bone
Silicified / Mineralized Fossil (Silica SiO2)
fossil
Jasper containing fossilized inclusions
Silicon Dioxide (SiO2) with trace impurities and biogenic inclusions
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Petrified Wood
Silicified Wood (SiO2)
fossil
Limestone with Gastropod Fossil
Sedimentary Calcium Carbonate (CaCO3) with Gastropoda inclusion
fossil
Sea Shell (Mollusk Shell)
Calcium Carbonate (Aragonite/Calcite)
fossil
Fossil Shark Tooth
Carcharodon sp. (likely Otodus or similar Lamniformes order)
sedimentary
Soil with Mineral Detritus and Quartz Fragments
Regolith / Silicate Mineral Aggregate
sedimentary
Chert Nodules in Limestone
Cryptocrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
sedimentary
Amber
Succinates (Organic Fossilized Resin)
mineral
Druzy Chalcedony/Quartz on Fluorite core
Silicon Dioxide (SiO2) on Calcium Fluoride (CaF2)
mineral
Grass (Organic Matter/Soil)
Poaceae (family of monocotyledonous flowering plants)
Organic Materia (Not a rock or mineral)
Amber
Succinite (amorphous organic polymer)
mineral