Concretion
Septarian or Siderite Concretion
sedimentary
Category
Mineral (Organic)
Browse mineral (organic) specimens identified by the Rock Identifier community.
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Limonite (Iron Ore)
Limonite (Hydrated iron(III) oxide-hydroxide, FeO(OH)·nH2O)
mineral
Chalcedony / Agate with Botryoidal Quartz
Silicon Dioxide (SiO2)
sedimentary
Chert / Flint
Chert (SiO2)
sedimentary
Shungite
Non-crystalline carbon (allotrope of carbon)
metamorphic
Glauconitic Sandstone
Glauconitic Sandstone (contains (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)
sedimentary
Banded Chert
Silicon Dioxide (SiO2) with impurities
sedimentary
Lemon (Mock specimen mimicking Citrine/Sulfur)
Citrus x limon
Organic (Biological specimen)
Fossil Shark Tooth
Carcharodon or Carcharias fossil (Vertebrate Fossil)
sedimentary
Mother of Pearl (Nacre)
Nacre (Aragonite/Conchiolin), CaCO3 + Organic Polymers
mineral
Polished amber-like chalcedony/jasper
Microcrystalline quartz (SiO₂), likely iron-stained chalcedony or jasper; amber cannot be confirmed visually
mineral
Amber
Succinite (fossilized resin)
mineral
Oyster Shell Fragment
Crassostrea virginica (or related Bivalvia)
fossil
Sandstone
Arenite
sedimentary
Fossiliferous Sandstone / Mudstone
Sedimentary Rock (Clastic with Fossiliferous Inclusions)
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Banded Chert
Microcrystalline Quartz (SiO2)
sedimentary
Amber
Succinates (fossilized tree resin), approximately C10H16O
organic gemstone
Jasper
Silicon dioxide (SiO2)
sedimentary
Shale (or Slate / Coal / Jet)
Laminated fine-grained sedimentary rock (predominantly clay minerals)
sedimentary
Petrified Wood
Silicified wood (SiO2)
fossil
Pearl
Calcium Carbonate (Aragonite) with Conchiolin; formula: CaCO3
mineral
Petrified Wood Fragment
Silicified Wood (SiO2)
fossil
Fossilized bone, likely a large vertebrate limb or rib fragment
Petrified bone; exact taxon indeterminate from the image
fossil
Polished chalcedony (likely moss/ag ate)
Microcrystalline quartz, SiO₂; probable moss agate or jasper variety
mineral
Tumbled agate (likely moss or plume agate)
Microcrystalline quartz, primarily chalcedony (SiO₂), with iron-oxide and other mineral inclusions
mineral
Amber
Succinite (Fossilized Tree Resin, C10H16O)
mineral
Amber
Organic gemstone (Succinite is common if from the Baltic)
mineral
Moss Agate
Chalcedony (Silicon Dioxide / SiO2)
mineral
Moss Agate
Silicon Dioxide with inclusions (SiO2)
mineral
Fossil tooth fragment
Likely fossilized shark tooth or marine vertebrate tooth; exact taxon cannot be determined from the image
fossil
Fossil Coral / Crinoid Stem section
Anthozoa / Crinoidea fossil
fossil
Natural White Pearl
Calcium Carbonate (Aragonite/Calcite) with Conchiolin - CaCO3
mineraloid
Fossilized Bone
Permineralized Vertebrate Bone
fossil
Amber beads
Amber, fossilized plant resin; largely polymerized terpenoid resin (not a mineral)
gemstone
Fossil plant impression slab
Fossilized plant compression/impression; exact taxon indeterminate from the image
fossil
Green Moss Agate / Jasper
Silicon Dioxide (SiO2) - Microcrystalline Quartz with Iron and Manganese inclusions
sedimentary
Amber
Fossilized Tree Resin (C10H16O)
gemstone
Amber
Succinite (specifically for Baltic amber); chemical formula approx. C10H16O
Organic Gemstone (fossilized resin)
Fossilized tooth, likely a mammalian tooth fragment
Indeterminate fossil tooth; possibly an ungulate or carnivoran tooth
fossil
Petrified Wood
Silicified Wood (primarily Silicon Dioxide, SiO2)
mineral
Amber
Succinite (Formula: C10H16O)
Mineraloid