Orbicular jasper (likely ocean jasper)
Silica-rich microcrystalline quartz/chalcedony with iron-oxide and feldspar inclusions; commonly marketed as Ocean Jasper
mineral
Category
Mineral (Biogenic Replacement)
Browse mineral (biogenic replacement) specimens identified by the Rock Identifier community.
Chalcedony in Matrix (likely Agatized Coral or Chert)
Silicon Dioxide (SiO2)
sedimentary
Petoskey Stone
Hexagonaria percarinata
fossil
Fossilized Shark Tooth
Bioapatite (Calcium Hydroxyapatite) replacement
mineral
Fossilized Trilobite or Mollusk Fragment
Phylum Arthropoda / Mollusca fossil in sedimentary matrix
fossil
Ammonite Fossil
Ammonoidea
fossil
Green Jasper
Silicon Dioxide (SiO2) with iron silicate inclusions
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Red Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Chert Pebble with Quartz Veins
Microcrystalline Quartz (SiO2)
sedimentary
Tiger's Eye
Pseudomorph of quartz after crocidolite (SiO2 with iron inclusions)
metamorphic
Popcorn
Zea mays everta (P. Wilson) (Botanical name for the corn variety)
Organic/Biogenic
Galena-bearing ore (tentative)
Galena, lead sulfide (PbS), likely in a quartz/carbonate-rich matrix
mineral
Chalcedony
Silicon Dioxide (SiO2)
mineral
Barite
Barium Sulfate (BaSO4)
mineral
Fossil tooth, possibly shark tooth
Indeterminate fossilized vertebrate tooth; likely a shark tooth (possibly *Carcharhinus* or related genus)
fossil
Lapis Lazuli (Tumbled)
Lazurite-dominated contact metamorphic rock
metamorphic
Yellow Jasper
Quartz (Silicon Dioxide, SiO2 with impurities)
sedimentary
Tiger's Eye
Silicon dioxide (Quartz pseudomorph after crocidolite), SiO2
gemstone
Fossil Coral
Scleractinia (Fossilized Coral) / Calcium Carbonate (CaCO3) or Silica (SiO2)
fossil
Jasper-Agate (Iron-stained Quartz)
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Red Jasper
Jasper (Silicon Dioxide, SiO2 with iron oxide impurities)
sedimentary
Petoskey Stone
Hexagonaria percarinata (Fossilized Rugose Coral)
sedimentary
Celestine (Celestite)
Celestine (Strontium Sulfate, SrSO4)
mineral
Chalcedony (Common Agate)
Silicon Dioxide (SiO2)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Rhodonite
Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3
mineral
Jasper
Silicon dioxide, SiO2
Mineral
Tumbled yellow jasper (likely serpentine or calcite-rich stone)
Jasper: microcrystalline quartz (SiO₂); exact yellow veining may indicate serpentine, calcite, or iron oxides
mineral
Chert (Jasper variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Vuggy or Fossilliferous)
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified wood (primarily SiO2 - Silicon Dioxide)
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Pyrite
Iron Sulfide (FeS2)
mineral
Chert with Druzy Quartz and Mossy/Iron Inclusions
Microcrystalline Quartz (SiO2)
sedimentary
Yellow Chert (Yellow Jasper)
Silicon dioxide (SiO2)
sedimentary
Iron-rich botryoidal limonite/goethite specimen
Limonite (amorphous hydrated iron oxides, chiefly goethite, α-FeO(OH))
mineral
Tiger's Eye (Nodule/Tumbled)
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron inclusions)
metamorphic
Fossilized coral (likely honeycomb or branching coral)
Fossil coral; probable Scleractinia or Tabulata, composition mainly microcrystalline CaCO₃
fossil
Fossil shark teeth
Probably fossilized shark teeth, possibly *Otodus* or *Carcharhinus* species
fossil
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
metamorphic
Fossilized Coral
Rugosa / Tabulata coral fossils replaced by silica (Chalcedony/Quartz)
fossil