Rock Identifier

Category

Mineral (Biogenic Replacement)

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

Fossilized Wood (Petrified Wood) (Silicified Wood (primarily quartz/chalcedony replacing organic matter)) — Sedimentary (with some aspects of mineral replacement)

Fossilized Wood (Petrified Wood)

Silicified Wood (primarily quartz/chalcedony replacing organic matter)

Sedimentary (with some aspects of mineral replacement)

Ammonite Fossil (Ammonoidea) — fossil

Ammonite Fossil

Ammonoidea

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)

Calcite (Calcite (CaCO3)) — Mineral

Calcite

Calcite (CaCO3)

Chert (Jasper) (Microcrystalline Quartz (SiO2) with iron oxide inclusions) — sedimentary

Chert (Jasper)

Microcrystalline Quartz (SiO2) with iron oxide inclusions

Flint Nodule (Microcrystalline Quartz (SiO2)) — sedimentary

Flint Nodule

Microcrystalline Quartz (SiO2)

Chert with Druzy Quartz Geode (Microcrystalline Quartz (SiO2)) — sedimentary

Chert with Druzy Quartz Geode

Microcrystalline Quartz (SiO2)

Tiger's Eye (Blue-Gold transition) (Pseudomorph of Quartz after Crocidolite (SiO2)) — metamorphic

Tiger's Eye (Blue-Gold transition)

Pseudomorph of Quartz after Crocidolite (SiO2)

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

Chert (and Flint)

Silicon Dioxide (SiO2)

Petrified Wood (Silicified Wood) (Silicified Wood / Silicon Dioxide (SiO2)) — metamorphic

Petrified Wood (Silicified Wood)

Silicified Wood / Silicon Dioxide (SiO2)

Petrified Wood (Silicified wood (Quartz/Chalcedony replacement)) — fossil

Petrified Wood

Silicified wood (Quartz/Chalcedony replacement)

Weathered chert or siliceous limestone (Microcrystalline quartz (SiO₂), possibly with carbonate minerals) — sedimentary

Weathered chert or siliceous limestone

Microcrystalline quartz (SiO₂), possibly with carbonate minerals

Petrified Wood (Silicified Wood (primarily SiO2)) — sedimentary

Petrified Wood

Silicified Wood (primarily SiO2)

Fossil Coral (Rugose Coral / Horn Coral Cross-Section) (Rugosa (Order) / Calcite (CaCO3)) — fossil

Fossil Coral (Rugose Coral / Horn Coral Cross-Section)

Rugosa (Order) / Calcite (CaCO3)

Petrified Wood (Silicified Wood (SiO2)) — fossil

Petrified Wood

Silicified Wood (SiO2)

Red Jasper (Tumbled) (Silicon Dioxide (SiO2) with iron oxide inclusions) — sedimentary/mineral

Red Jasper (Tumbled)

Silicon Dioxide (SiO2) with iron oxide inclusions

sedimentary/mineral

Petrified Wood (Silicified wood (Quartz/Chalcedony replacement)) — fossil

Petrified Wood

Silicified wood (Quartz/Chalcedony replacement)

Tiger's Eye (Tiger's Eye (a variety of Chalcedony, which is a microcrystalline quartz with fibrous inclusions of oxidized crocidolite)) — Mineral

Tiger's Eye

Tiger's Eye (a variety of Chalcedony, which is a microcrystalline quartz with fibrous inclusions of oxidized crocidolite)

Chert (variations include Flint or Jasper) (Silicon Dioxide (SiO2)) — sedimentary

Chert (variations include Flint or Jasper)

Silicon Dioxide (SiO2)

Orbicular jasper (picture jasper) (Silicified volcanic or sedimentary rock; chiefly microcrystalline quartz (SiO₂) with iron-oxide pigments) — sedimentary

Orbicular jasper (picture jasper)

Silicified volcanic or sedimentary rock; chiefly microcrystalline quartz (SiO₂) with iron-oxide pigments

Petrified Wood (Agatized/Silicified Wood) (Silicified Wood (SiO2 - Silicon Dioxide)) — metamorphic

Petrified Wood (Agatized/Silicified Wood)

Silicified Wood (SiO2 - Silicon Dioxide)

Petrified Wood (Silicified Wood (SiO2 - Silicon Dioxide)) — sedimentary

Petrified Wood

Silicified Wood (SiO2 - Silicon Dioxide)

Petrified Wood (Silicified wood, primarily composed of Quartz (SiO2)) — Mineral, often found in sedimentary deposits

Petrified Wood

Silicified wood, primarily composed of Quartz (SiO2)

Mineral, often found in sedimentary deposits

Pyrite (Pyrite (Iron sulfide, FeS₂)) — Mineral

Pyrite

Pyrite (Iron sulfide, FeS₂)

Larimar (Blue Pectolite (NaCa2Si3O8(OH))) — mineral

Larimar

Blue Pectolite (NaCa2Si3O8(OH))

Limonite-pseudomorph after Pyrite (Prophecy Stone) (Goethite and Limonite secondary minerals (FeO(OH)·nH2O) replacing Pyrite (FeS2)) — mineral

Limonite-pseudomorph after Pyrite (Prophecy Stone)

Goethite and Limonite secondary minerals (FeO(OH)·nH2O) replacing Pyrite (FeS2)

Fossilized Bivalve Shell (Fossilized Clam) (Bivalvia (class) / CaCO3 (Calcium Carbonate)) — fossil

Fossilized Bivalve Shell (Fossilized Clam)

Bivalvia (class) / CaCO3 (Calcium Carbonate)

Chert (with Iron Staining) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (with Iron Staining)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Red Jasper (Red Jasper (variety of Chalcedony, SiO₂)) — Mineral

Red Jasper

Red Jasper (variety of Chalcedony, SiO₂)

Chert / Flint (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert / Flint

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Red Jasper (Jasper (Silicon Dioxide with iron oxide inclusions), SiO2) — mineral

Red Jasper

Jasper (Silicon Dioxide with iron oxide inclusions), SiO2

Petrified Wood (Silicified wood (Quartz/Chalcedony replacement of cellulose)) — fossil

Petrified Wood

Silicified wood (Quartz/Chalcedony replacement of cellulose)

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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Petrified Wood (Silicified Wood (primarily SiO2 - Silicon Dioxide)) — sedimentary

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)

Chert (with Limonite staining) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (with Limonite staining)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Bismuth Crystal (Bismuth (Bi)) — mineral

Bismuth Crystal

Bismuth (Bi)

Likely iron-rich chert or jasper (Microcrystalline quartz (SiO₂), variably stained by iron oxides/hydroxides) — sedimentary

Likely iron-rich chert or jasper

Microcrystalline quartz (SiO₂), variably stained by iron oxides/hydroxides

Petrified Wood (Silicified Wood (SiO2 - Quartz/Chalcendony replacing organic matter)) — sedimentary

Petrified Wood

Silicified Wood (SiO2 - Quartz/Chalcendony replacing organic matter)

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

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Amber Inlay Jewelry (Fossilized Resin (C10H16O)) — Organic Gemstone (Biogenic)

Amber Inlay Jewelry

Fossilized Resin (C10H16O)

Organic Gemstone (Biogenic)

Petoskey Stone (Fossilized Coral) (Hexagonaria percarinata) — fossil

Petoskey Stone (Fossilized Coral)

Hexagonaria percarinata

Echinoid Fossil (Sea Urchin) (Echinoidea (specifically likely Schizaster or similar genus), calcium carbonate (CaCO3)) — sedimentary

Echinoid Fossil (Sea Urchin)

Echinoidea (specifically likely Schizaster or similar genus), calcium carbonate (CaCO3)