Rock Identifier

Category

Mineral (Biogenic Replacement)

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

Fossil trilobite (Trilobita (likely a spiny or enrolled trilobite; exact genus unclear)) — fossil

Fossil trilobite

Trilobita (likely a spiny or enrolled trilobite; exact genus unclear)

Fossil bivalve shell in matrix (Likely fossilized oyster or mussel (Bivalvia), with a nacreous aragonite shell; exact genus and age require locality and preparation details) — fossil

Fossil bivalve shell in matrix

Likely fossilized oyster or mussel (Bivalvia), with a nacreous aragonite shell; exact genus and age require locality and preparation details

Fossil gastropod in granite-like stone (Gastropoda indet.; enclosing rock likely polished granite or gneiss) — fossil

Fossil gastropod in granite-like stone

Gastropoda indet.; enclosing rock likely polished granite or gneiss

Likely galena (lead ore) (Galena, PbS (lead sulfide)) — mineral

Likely galena (lead ore)

Galena, PbS (lead sulfide)

Iron-oxide-stained jasper or weathered ironstone (Microcrystalline quartz (SiO₂) with hematite/goethite and probable clay minerals) — mineral

Iron-oxide-stained jasper or weathered ironstone

Microcrystalline quartz (SiO₂) with hematite/goethite and probable clay minerals

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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Polished/tumbled brown-and-white mineral fragment (Indeterminate; possibly quartz-rich jasper, brecciated jasper, or an iron-stained quartz mineral) — mineral

Polished/tumbled brown-and-white mineral fragment

Indeterminate; possibly quartz-rich jasper, brecciated jasper, or an iron-stained quartz mineral

Weathered iron-rich stone, possibly jasper or chert (Microcrystalline quartz (SiO₂), likely stained by iron oxides/hydroxides) — mineral

Weathered iron-rich stone, possibly jasper or chert

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

Jasper (Silicon Dioxide (SiO2)) — mineral

Jasper

Silicon Dioxide (SiO2)

Magnetite (or Magnetic Iron Ore) (Magnetite (Fe3O4)) — mineral

Magnetite (or Magnetic Iron Ore)

Magnetite (Fe3O4)

Galena (Galena (lead sulfide, PbS)) — mineral

Galena

Galena (lead sulfide, PbS)

Blue Sphalerite (likely dyed or treated Druzy Quartz/Agate) (Zinc Sulfide (ZnS) or Silicon Dioxide (SiO2) with trade-name enhancement) — Mineral

Blue Sphalerite (likely dyed or treated Druzy Quartz/Agate)

Zinc Sulfide (ZnS) or Silicon Dioxide (SiO2) with trade-name enhancement

Vuggy Chert / Silicified Limestone (Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions) — sedimentary

Vuggy Chert / Silicified Limestone

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Fossilized bivalve or brachiopod shell (Indeterminate calcitic shell fossil; likely Bivalvia or Brachiopoda) — fossil

Fossilized bivalve or brachiopod shell

Indeterminate calcitic shell fossil; likely Bivalvia or Brachiopoda

Chert (often called Flint when dark or found in chalk) (Microcrystalline or Cryptocrystalline Quartz (SiO2)) — sedimentary

Chert (often called Flint when dark or found in chalk)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Fossilized Coral (Cnidaria fossil / Calcite-replaced coral) — fossil

Fossilized Coral

Cnidaria fossil / Calcite-replaced coral

Tumbled Stones Collection (Tiger's Eye, Snowflake Obsidian, Aventurine, etc.) (Silica minerals (primarily SiO2)) — mineral

Tumbled Stones Collection (Tiger's Eye, Snowflake Obsidian, Aventurine, etc.)

Silica minerals (primarily SiO2)

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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron inclusions)

Flint / Chert with Cortex (Microcrystalline Quartz (SiO2)) — sedimentary

Flint / Chert with Cortex

Microcrystalline Quartz (SiO2)

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

Tiger's Eye (Unpolished)

Pseudomorph of Quartz after Crocidolite (SiO2)

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

Petrified Wood

Silicified wood (primarily SiO2)

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

Petrified Wood

Silicon Dioxide (SiO2) - Calcified / Silicified Wood

Banded fluorite point (Fluorite (calcium fluoride, CaF₂)) — mineral

Banded fluorite point

Fluorite (calcium fluoride, CaF₂)

Native metal specimen, likely galena or metallic slag (Probably galena (lead sulfide, PbS); identification is uncertain from the image alone) — mineral

Native metal specimen, likely galena or metallic slag

Probably galena (lead sulfide, PbS); identification is uncertain from the image alone

Fluorite (Rainbow Fluorite) (Calcium Fluoride (CaF2)) — mineral

Fluorite (Rainbow Fluorite)

Calcium Fluoride (CaF2)

Galena (Lead(II) sulfide (PbS)) — mineral

Galena

Lead(II) sulfide (PbS)

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

Tiger's Eye

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

Fossilized shell, likely gastropod or bivalve (Recrystallized carbonate fossil; original shell likely aragonite or calcite (taxon indeterminate)) — fossil

Fossilized shell, likely gastropod or bivalve

Recrystallized carbonate fossil; original shell likely aragonite or calcite (taxon indeterminate)

Tumbled orbicular jasper (likely ocean jasper) (Silicified volcanic rock; mainly microcrystalline quartz (SiO₂) with iron oxides and other accessory minerals) — metamorphic

Tumbled orbicular jasper (likely ocean jasper)

Silicified volcanic rock; mainly microcrystalline quartz (SiO₂) with iron oxides and other accessory minerals

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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Popcorn (Zea mays everta (P. Wilson) (Botanical name for the corn variety)) — Organic/Biogenic

Popcorn

Zea mays everta (P. Wilson) (Botanical name for the corn variety)

Organic/Biogenic

Fossil gastropod shell (Fossilized marine gastropod; exact genus/species requires locality and examination) — fossil

Fossil gastropod shell

Fossilized marine gastropod; exact genus/species requires locality and examination

Banded Chert (Iron-stained) (Microcrystalline Quartz (SiO2) with Iron Oxides) — sedimentary

Banded Chert (Iron-stained)

Microcrystalline Quartz (SiO2) with Iron Oxides

Fossilized Coral (Favosites) (Favosites goldfussi / Tabulata) — sedimentary

Fossilized Coral (Favosites)

Favosites goldfussi / Tabulata

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

Flint

SiO2 (Microcrystalline Quartz / Chert)

Yellow Jade (often Serpentine or Dolomite) (Primarily Serpentine (Mg3Si2O5(OH)4) or Dolomite (CaMg(CO3)2), though the term 'yellow jade' is also sometimes applied to varieties of true nephrite or jadeite.) — Mineral, often a rock given its aggregate nature

Yellow Jade (often Serpentine or Dolomite)

Primarily Serpentine (Mg3Si2O5(OH)4) or Dolomite (CaMg(CO3)2), though the term 'yellow jade' is also sometimes applied to varieties of true nephrite or jadeite.

Mineral, often a rock given its aggregate nature

Botryoidal iron-stained quartz/chalcedony (Microcrystalline quartz (SiO₂), likely chalcedony with limonite/goethite coatings) — mineral

Botryoidal iron-stained quartz/chalcedony

Microcrystalline quartz (SiO₂), likely chalcedony with limonite/goethite coatings

Sphalerite with quartz (Sphalerite (ZnS), associated with quartz (SiO₂)) — mineral

Sphalerite with quartz

Sphalerite (ZnS), associated with quartz (SiO₂)

Wollastonite (Calcium Inosilicate Mineral, CaSiO3) — mineral

Wollastonite

Calcium Inosilicate Mineral, CaSiO3

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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

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

Celestine (Celestite)

Strontium Sulfate (SrSO4)

Flint (Silicon dioxide (SiO2)) — sedimentary

Flint

Silicon dioxide (SiO2)