Chert
Microcrystalline or cryptocrystalline quartz (SiO2)
sedimentary
Category
Sedimentary (With Some Aspects Of Mineral Replacement)
Browse sedimentary (with some aspects of mineral replacement) specimens identified by the Rock Identifier community.
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Flint
SiO2 (Microcrystalline Quartz / Chert)
sedimentary
Flint
SiO2 (Cryptocrystalline Quartz)
sedimentary
Flint
Cryptocrystalline quartz (SiO2)
sedimentary
Flint / Chert
Silicon dioxide (Microcrystalline quartz, SiO2)
sedimentary
Peacock Ore (Chalcopyrite)
Chalcopyrite (CuFeS2)
mineral
Fossilized Coral
Hexagonaria (Rugose and Tabulate coral fossils)
fossil
Chert (or Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Fossil bivalve or brachiopod in sedimentary rock
Unidentified fossil shell impression; likely a ribbed bivalve or brachiopod preserved in shale/siltstone
fossil
Siderite Concretion
Ironstone (Siderite) Concretion, FeCO3
sedimentary
Chert (Common Opal variant)
Silicon Dioxide (SiO2)
sedimentary
Chert (Green Chert/Jasper)
Chert (primarily Microcrystalline Quartz, SiO2)
sedimentary
Megalodon Shark Tooth Fossil
Otodus megalodon (fossilized in sedimentary matrix)
sedimentary
Mica Schist
Mica Schist (KAl2(AlSi3O10)(OH)2)
metamorphic
Chert (Flint)
Chert (Silicon Dioxide, SiO2)
sedimentary
Shale
Fissile Mudstone (Shale)
sedimentary
Sandstone (Ferruginous)
Arenite (Fe-rich)
sedimentary
Chert / Flint Nodules
Cryptocrystalline Quartz (SiO2)
sedimentary
Fossilized Shark Tooth
Chondrichthyes (Class) fossilized tooth
fossil
Sandstone
Arenite (SiO2 principal)
sedimentary
Concretion
Sedimentary Concretion (e.g., Siderite or Ironstone)
sedimentary
Sandstone
Clastic sedimentary rock (primarily quartz arenite)
sedimentary
Jasper (Brown Iron-Rich Variety)
Silicon Dioxide (SiO2) with Fe2O3 (Iron Oxide/Crystalline Quartz)
sedimentary
Banded Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Fossilized Bone (Petrified Bone)
Permineralized Bone Fossil
fossil
Gneiss
Gneiss
metamorphic
Fossilized Brachiopod
Brachiopoda (e.g., Atrypa or Rhynchonellida)
fossil
Fossil bivalve shell
Fossilized mollusk (Bivalvia), likely an oyster or clam; exact genus requires locality and diagnostic features
fossil
Fossil bivalve shell
Calcitic aragonitic bivalve mollusk shell; exact taxon cannot be determined from the image
fossil
Pyrite
Iron Sulfide (FeS2)
mineral
Fossilized Coral
Anthozoa (Fossilized)
Sedimentary / Fossil
Petrified wood
Silicified wood; commonly quartz (SiO₂) replacing original woody tissue
fossil
Gold-bearing pyrite-rich rock (iron pyrite)
Pyrite, FeS₂, likely in a quartz- or sulfide-rich matrix
mineral
Botryoidal Chalcedony (Quartz Var.)
Silicon Dioxide (SiO2)
mineral
Red Jasper
Silicon Dioxide (SiO2) with Hematite impurities
mineral
Chert (specifically Jasper/Carnelian Agate)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Agatized/Chalcedony variety)
Microcrystalline Quartz (SiO2)
sedimentary
Banded gneiss
Gneiss, composed mainly of quartz, feldspar, and mica
metamorphic
Zebra Jasper
Tektite variety of Silicon Dioxide (SiO2) with inclusions
sedimentary
Chalcedony (possibly agate or common quartz)
Microcrystalline quartz, SiO₂
mineral
Polished orbicular jasper (likely ocean jasper)
Silicified microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions
gemstone
Fossilized Bone
Vertebrate Fossil Fragment (Calcium Phosphate / Hydroxyapatite)
fossil