Rock Identifier

Category

Biogenic Material

Browse biogenic material specimens identified by the Rock Identifier community.

Learn about Biogenic Material in the encyclopedia

Peat

Diatomite

Dunite

Limonite

Diamond

Peacock Opal

Metarhyolite

Rhodochrosite

Shell Opal

Madagascar Opal

Lavender Obsidian

Electric Blue Obsidian

Polished dark green stone, likely nephrite jade or serpentine (Nephrite jade: tremolite–actinolite amphibole, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂; possible serpentine: Mg₃Si₂O₅(OH)₄) — metamorphic

Polished dark green stone, likely nephrite jade or serpentine

Nephrite jade: tremolite–actinolite amphibole, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂; possible serpentine: Mg₃Si₂O₅(OH)₄

Yellow chalcedony (likely heat-treated or resin-coated) (Microcrystalline quartz, SiO₂) — mineral

Yellow chalcedony (likely heat-treated or resin-coated)

Microcrystalline quartz, SiO₂

Likely polished garnet fragment (Garnet group, possibly almandine (Fe₃Al₂Si₃O₁₂)) — gemstone

Likely polished garnet fragment

Garnet group, possibly almandine (Fe₃Al₂Si₃O₁₂)

Speckled rounded stone, likely granite or granitic gneiss (Granite/granitic gneiss; primarily quartz (SiO₂), feldspar, and dark mica or amphibole) — igneous

Speckled rounded stone, likely granite or granitic gneiss

Granite/granitic gneiss; primarily quartz (SiO₂), feldspar, and dark mica or amphibole

Fossilized ammonite (likely weathered ammonite cross-section) (Ammonoidea; commonly Jurassic–Cretaceous ammonite fossils replaced by calcite or aragonite) — fossil

Fossilized ammonite (likely weathered ammonite cross-section)

Ammonoidea; commonly Jurassic–Cretaceous ammonite fossils replaced by calcite or aragonite

Rough Diamond (Carbon (C)) — mineral

Rough Diamond

Carbon (C)

Fossilized Brachiopod (Phylum Brachiopoda (likely Order Spiriferida or Orthida)) — fossil

Fossilized Brachiopod

Phylum Brachiopoda (likely Order Spiriferida or Orthida)

Yellow-brown quartz/chalcedony fragment (Quartz, SiO₂; likely microcrystalline chalcedony with iron-oxide staining) — mineral

Yellow-brown quartz/chalcedony fragment

Quartz, SiO₂; likely microcrystalline chalcedony with iron-oxide staining

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

Chert (Flint)

Silicon Dioxide (SiO2)

Fossil brachiopod or bivalve shell (Likely a fossilized brachiopod; precise genus cannot be determined from the photograph) — fossil

Fossil brachiopod or bivalve shell

Likely a fossilized brachiopod; precise genus cannot be determined from the photograph

Polished agate slice (Agate, a banded variety of chalcedony (microcrystalline SiO₂)) — mineral

Polished agate slice

Agate, a banded variety of chalcedony (microcrystalline SiO₂)

Dark gray basalt or andesite cobble (Fine-grained mafic to intermediate volcanic rock; commonly plagioclase feldspar, pyroxene, and possibly olivine) — igneous

Dark gray basalt or andesite cobble

Fine-grained mafic to intermediate volcanic rock; commonly plagioclase feldspar, pyroxene, and possibly olivine

Tumbled ruby-bearing corundum (Corundum (Al₂O₃), likely ruby variety) — mineral

Tumbled ruby-bearing corundum

Corundum (Al₂O₃), likely ruby variety

Carved lavender chalcedony (likely agate) animal figurine (Microcrystalline quartz, SiO₂; probable chalcedony or pale lavender agate) — gemstone

Carved lavender chalcedony (likely agate) animal figurine

Microcrystalline quartz, SiO₂; probable chalcedony or pale lavender agate

Chert or flint nodule (Microcrystalline quartz (SiO₂), likely chalcedony-rich chert) — sedimentary

Chert or flint nodule

Microcrystalline quartz (SiO₂), likely chalcedony-rich chert

Polished dendritic jasper or agate slab (Microcrystalline quartz (SiO₂), likely jasper with chalcedony and iron/manganese dendrites) — mineral

Polished dendritic jasper or agate slab

Microcrystalline quartz (SiO₂), likely jasper with chalcedony and iron/manganese dendrites

Possible tektite or iron-rich slag-like natural specimen (Uncertain; possibly natural glass (tektite) or magnetite-rich rock) — mineral

Possible tektite or iron-rich slag-like natural specimen

Uncertain; possibly natural glass (tektite) or magnetite-rich rock

Polished black obsidian pyramid/block (Obsidian — natural volcanic glass, chiefly rhyolitic silica (approximately 70–75% SiO₂)) — igneous

Polished black obsidian pyramid/block

Obsidian — natural volcanic glass, chiefly rhyolitic silica (approximately 70–75% SiO₂)

Diamond (Carbon (C)) — gemstone

Diamond

Carbon (C)

Quartzite (Quartzite (primarily SiO2)) — metamorphic

Quartzite

Quartzite (primarily SiO2)

Small white mineral fragment (Indeterminate; possibly quartz, calcite, or feldspar) — mineral

Small white mineral fragment

Indeterminate; possibly quartz, calcite, or feldspar

Amethyst cluster (Amethyst, purple quartz (SiO₂)) — mineral

Amethyst cluster

Amethyst, purple quartz (SiO₂)

Blue calcite (likely) (Calcite, CaCO₃) — mineral

Blue calcite (likely)

Calcite, CaCO₃

Dalmatian jasper (Dalmatian stone, typically a leucocratic alkali-feldspar-rich porphyritic igneous rock with black arfvedsonite or aegirine inclusions) — igneous

Dalmatian jasper

Dalmatian stone, typically a leucocratic alkali-feldspar-rich porphyritic igneous rock with black arfvedsonite or aegirine inclusions

Staurolite-bearing mica schist (probable) (Mica schist composed chiefly of muscovite/biotite, quartz, and likely staurolite or garnet) — metamorphic

Staurolite-bearing mica schist (probable)

Mica schist composed chiefly of muscovite/biotite, quartz, and likely staurolite or garnet

Rose quartz heart (Quartz, silicon dioxide (SiO₂), pink variety) — mineral

Rose quartz heart

Quartz, silicon dioxide (SiO₂), pink variety

Blue topaz (likely treated) (Topaz, Al₂SiO₄(F,OH)₂) — gemstone

Blue topaz (likely treated)

Topaz, Al₂SiO₄(F,OH)₂

Chert (or Jasper) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (or Jasper)

Microcrystalline Quartz (SiO2)

Diamond (Carbon (C)) — gemstone

Diamond

Carbon (C)

Opalite (Synthetic glass / Opalized glass) — gemstone

Opalite

Synthetic glass / Opalized glass

Fossil Coral (Scleractinia (Fossilized Coral)) — fossil

Fossil Coral

Scleractinia (Fossilized Coral)

Limestone (Calcium Carbonate (CaCO3)) — sedimentary

Limestone

Calcium Carbonate (CaCO3)

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

Chert (Black Flint)

Silicon Dioxide (SiO2)

Red Sandstone (Arenite (Iron-rich)) — sedimentary

Red Sandstone

Arenite (Iron-rich)

$Orange Crackle Quartz (Silicon Dioxide (SiO2) with thermal fracturing) — mineral$

Orange Crackle Quartz

Silicon Dioxide (SiO2) with thermal fracturing

Turritella Fossil (Turritella (Class Gastropoda, Family Turritellidae)) — fossil

Turritella Fossil

Turritella (Class Gastropoda, Family Turritellidae)

Flint (Chert (SiO2)) — sedimentary

Flint

Chert (SiO2)

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

Chert (Flint)

Silicon Dioxide (SiO2)

Sandstone (Quartzose) (Sandstone (composed primarily of Quartz: SiO2)) — sedimentary

Sandstone (Quartzose)

Sandstone (composed primarily of Quartz: SiO2)

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

Chert (Flint)

Microcrystalline Quartz (SiO2)

Slate Pebble (Low-grade Metamorphosed Shale (Slate)) — metamorphic

Slate Pebble

Low-grade Metamorphosed Shale (Slate)

Chert (Flint) (Chert (SiO2)) — sedimentary

Chert (Flint)

Chert (SiO2)