Rock Identifier

Category

Mineral (Biogenic Replacement)

Browse mineral (biogenic replacement) specimens identified by the Rock Identifier community.

Fossilized oyster shell (Bivalvia; likely an oyster (Ostreidae), partly mineralized with calcite) — fossil

Fossilized oyster shell

Bivalvia; likely an oyster (Ostreidae), partly mineralized with calcite

Quartz-rich rock, likely chert or chalcedony (Microcrystalline silica (SiO₂), possibly quartz/chalcedony) — mineral

Quartz-rich rock, likely chert or chalcedony

Microcrystalline silica (SiO₂), possibly quartz/chalcedony

Tiger's Eye (and Hematite/Jasper Matrix) (SiO2 (Pseudomorph of Quartz after Crocidolite) with Hematite/Magnetite) — mineral

Tiger's Eye (and Hematite/Jasper Matrix)

SiO2 (Pseudomorph of Quartz after Crocidolite) with Hematite/Magnetite

Enrolled Trilobite Fossil (Phylum Arthropoda, Class Trilobita (likely Calymene or Flexicalymene)) — fossil

Enrolled Trilobite Fossil

Phylum Arthropoda, Class Trilobita (likely Calymene or Flexicalymene)

Horn Coral Fossil (Rugosa (Order Rugosa)) — fossil

Horn Coral Fossil

Rugosa (Order Rugosa)

Galena (Lead Sulfide (PbS)) — mineral

Galena

Lead Sulfide (PbS)

Red Jasper Concretion (Cryptocrystalline Quartz (SiO2)) — sedimentary

Red Jasper Concretion

Cryptocrystalline Quartz (SiO2)

Spinosaurus aegyptiacus Fossil (Spinosaurus aegyptiacus (permineralized hydroxyapatite)) — fossil

Spinosaurus aegyptiacus Fossil

Spinosaurus aegyptiacus (permineralized hydroxyapatite)

Chert (varieties include Flint and Jasper) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (varieties include Flint and Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint variety) (Silicon dioxide (SiO2) - Microcrystalline Quartz) — sedimentary

Chert (Flint variety)

Silicon dioxide (SiO2) - Microcrystalline Quartz

Chert (Jasper/Flint variety) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Lepidodendron fossil (Scale Tree Bark) (Lepidodendron (Lycophytina class)) — sedimentary

Lepidodendron fossil (Scale Tree Bark)

Lepidodendron (Lycophytina class)

Jasper (Red-Brown) (Silicon Dioxide (SiO2) with Iron Oxide impurities) — sedimentary

Jasper (Red-Brown)

Silicon Dioxide (SiO2) with Iron Oxide impurities

Fossil Coral (Rugose Coral or Tabulate Coral (Phylum Cnidaria)) — fossil

Fossil Coral

Rugose Coral or Tabulate Coral (Phylum Cnidaria)

Purple fluorite (likely cubic crystal aggregate) (Fluorite, calcium fluoride (CaF₂)) — mineral

Purple fluorite (likely cubic crystal aggregate)

Fluorite, calcium fluoride (CaF₂)

Jasper with Quartz Vein (Silicon Dioxide (SiO2) - Microcrystalline Quartz) — sedimentary

Jasper with Quartz Vein

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Tiger's Eye (Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)) — metamorphic

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)

Chert (Jasper) (Silicon dioxide (SiO2)) — sedimentary

Chert (Jasper)

Silicon dioxide (SiO2)

Tiger's Eye (Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxides)) — metamorphic

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxides)

Likely galena-bearing ore specimen (Galena (PbS), possibly with quartz or calcite gangue) — mineral

Likely galena-bearing ore specimen

Galena (PbS), possibly with quartz or calcite gangue

Botryoidal Chalcedony (Quartz Var.) (Silicon Dioxide (SiO2)) — mineral

Botryoidal Chalcedony (Quartz Var.)

Silicon Dioxide (SiO2)

Red Jasper (Silicon Dioxide (SiO2) with Hematite impurities) — mineral

Red Jasper

Silicon Dioxide (SiO2) with Hematite impurities

Petrified Wood (Silicified Wood (SiO2)) — sedimentary

Petrified Wood

Silicified Wood (SiO2)

Chert (with Quartz Veining) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (with Quartz Veining)

Microcrystalline Quartz (SiO2)

Tiger's Eye (Tiger's Eye (Pseudomorph of Quartz after Crocidolite), SiO2) — metamorphic

Tiger's Eye

Tiger's Eye (Pseudomorph of Quartz after Crocidolite), SiO2

Jasper (Jasper (Silicate mineral, SiO2)) — sedimentary

Jasper

Jasper (Silicate mineral, SiO2)

Chert (Limestone-based) (Silicon dioxide (SiO2)) — sedimentary

Chert (Limestone-based)

Silicon dioxide (SiO2)

Jasper (Jasper (SiO2)) — sedimentary

Jasper

Jasper (SiO2)

Jasper (Silicon dioxide (SiO2)) — Sedimentary / Mineral

Jasper

Silicon dioxide (SiO2)

Sedimentary / Mineral

Horn Coral Fossil (Rugose coral (Order Rugosa)) — fossil

Horn Coral Fossil

Rugose coral (Order Rugosa)

Chert (Flint) (Chert (Silicon Dioxide, SiO2)) — sedimentary

Chert (Flint)

Chert (Silicon Dioxide, SiO2)

Petrified Wood (Silicified Wood (SiO2)) — sedimentary

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood (Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)) — fossil

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)

Blue Tiger's Eye (Silicon Dioxide (SiO2) with Crocidolite inclusions) — Mineral (Pseudomorph)

Blue Tiger's Eye

Silicon Dioxide (SiO2) with Crocidolite inclusions

Mineral (Pseudomorph)

Celestite (Celestine) (Strontium sulfate (SrSO4)) — mineral

Celestite (Celestine)

Strontium sulfate (SrSO4)

Tiger's Eye (Pseudomorph of Quartz after Crocidolite (SiO2 with Iron Oxide inclusions)) — metamorphic

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with Iron Oxide inclusions)

Echinoid Fossil / Fossilized Sea Urchin (Echinoidea) — fossil

Echinoid Fossil / Fossilized Sea Urchin

Echinoidea

Fossilized Coral (Scleractinia (Agatized or Calcite replaced)) — fossil

Fossilized Coral

Scleractinia (Agatized or Calcite replaced)

Chert (Flint) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Flint)

Silicon Dioxide (SiO2)

Petrified Wood (Silicified Wood (SiO2 permineralization)) — fossil

Petrified Wood

Silicified Wood (SiO2 permineralization)

Chert (Nodule) (Silicon Dioxide (SiO2)) — sedimentary

Chert (Nodule)

Silicon Dioxide (SiO2)

Fossilized Trilobite Pygidium / Glabella Fragment (Trilobita (e.g., Phacops or Ceraurus sp.)) — fossil

Fossilized Trilobite Pygidium / Glabella Fragment

Trilobita (e.g., Phacops or Ceraurus sp.)