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

Weathered quartz-rich metamorphic rock (probable quartzite) (Quartzite; predominantly microcrystalline quartz (SiO₂), with possible mica, feldspar, and iron-oxide impurities) — metamorphic

Weathered quartz-rich metamorphic rock (probable quartzite)

Quartzite; predominantly microcrystalline quartz (SiO₂), with possible mica, feldspar, and iron-oxide impurities

Sedimentary Breccia (Clastic Breccia (CaCO3/SiO2 matrix)) — sedimentary

Sedimentary Breccia

Clastic Breccia (CaCO3/SiO2 matrix)

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

Rose quartz (polished fragment)

Quartz, silicon dioxide (SiO₂), pink variety

Porphyritic granite or granodiorite (Coarse-grained plutonic rock composed mainly of quartz (SiO₂), feldspar, and mica/amphibole) — igneous

Porphyritic granite or granodiorite

Coarse-grained plutonic rock composed mainly of quartz (SiO₂), feldspar, and mica/amphibole

Tumbled dark river pebble, probably basalt (Fine-grained mafic volcanic rock, most likely basalt; exact identification requires testing) — igneous

Tumbled dark river pebble, probably basalt

Fine-grained mafic volcanic rock, most likely basalt; exact identification requires testing

Tumbled pegmatitic granite (Coarse-grained granite/pegmatite, chiefly quartz, feldspar, and biotite or amphibole) — igneous

Tumbled pegmatitic granite

Coarse-grained granite/pegmatite, chiefly quartz, feldspar, and biotite or amphibole

Tumbled dark stone, likely basalt or basaltic pebble (Fine-grained mafic volcanic rock; commonly composed of plagioclase, pyroxene, and minor olivine (basalt)) — igneous

Tumbled dark stone, likely basalt or basaltic pebble

Fine-grained mafic volcanic rock; commonly composed of plagioclase, pyroxene, and minor olivine (basalt)

Coarse-grained granite or granitic gneiss (Granite; primarily quartz (SiO₂), feldspar, and mica, possibly metamorphosed to gneiss) — igneous

Coarse-grained granite or granitic gneiss

Granite; primarily quartz (SiO₂), feldspar, and mica, possibly metamorphosed to gneiss

Likely vesicular basalt (scoria) (Basaltic scoria; chiefly plagioclase, pyroxene, and olivine with vesicles) — igneous

Likely vesicular basalt (scoria)

Basaltic scoria; chiefly plagioclase, pyroxene, and olivine with vesicles

Quartz-rich metamorphic rock, likely quartzite (Quartzite; predominantly crystalline quartz (SiO₂), possibly with mica and feldspar) — metamorphic

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly crystalline quartz (SiO₂), possibly with mica and feldspar

Tumbled blue sodalite (probable) (Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂) — mineral

Tumbled blue sodalite (probable)

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂

Likely quartz crystal fragment (Quartz (SiO₂), possibly a small tumbled or cleaved fragment) — mineral

Likely quartz crystal fragment

Quartz (SiO₂), possibly a small tumbled or cleaved fragment

Quartz-rich rock, possibly milky quartz or quartzite (Quartz (SiO₂), potentially quartzite if the grains are fused) — mineral

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), potentially quartzite if the grains are fused

Conglomeratic breccia (Clast-supported polymictic conglomerate/breccia, cemented by silica- or carbonate-rich matrix) — sedimentary

Conglomeratic breccia

Clast-supported polymictic conglomerate/breccia, cemented by silica- or carbonate-rich matrix

Quartz geode (likely amethyst-bearing) (Silica geode; quartz, SiO₂, with possible amethyst and minor iron oxides) — mineral

Quartz geode (likely amethyst-bearing)

Silica geode; quartz, SiO₂, with possible amethyst and minor iron oxides

$Polished septarian nodule (Septarian concretion; calcite/aragonite and barite-filled fractures in a carbonate-rich mudstone, commonly with pyrite) — sedimentary$

Polished septarian nodule

Septarian concretion; calcite/aragonite and barite-filled fractures in a carbonate-rich mudstone, commonly with pyrite

Iron-rich chert or jasper (Microcrystalline quartz (SiO₂), colored by hematite/goethite inclusions) — sedimentary

Iron-rich chert or jasper

Microcrystalline quartz (SiO₂), colored by hematite/goethite inclusions

Pegmatitic granite (Coarse-grained granite, chiefly quartz, feldspar, and mica; likely a granitic pegmatite) — igneous

Pegmatitic granite

Coarse-grained granite, chiefly quartz, feldspar, and mica; likely a granitic pegmatite

Limestone (Calcium Carbonate (CaCO3)) — sedimentary

Limestone

Calcium Carbonate (CaCO3)

Dumortierite Quartz (Dumortierite-bearing Quartz (SiO2 with Al7BO3(SiO4)3O3)) — mineral

Dumortierite Quartz

Dumortierite-bearing Quartz (SiO2 with Al7BO3(SiO4)3O3)

Porphyritic Basalt (Extrusive igneous rock with plagioclase phenocrysts) — igneous

Porphyritic Basalt

Extrusive igneous rock with plagioclase phenocrysts

Limestone (Calcite rock (CaCO3)) — sedimentary

Limestone

Calcite rock (CaCO3)

Sandstone (Sedimentary Rock (Quartz Sandstone)) — sedimentary

Sandstone

Sedimentary Rock (Quartz Sandstone)

Quartz Pebble (Silicon Dioxide (SiO2)) — sedimentary

Quartz Pebble

Silicon Dioxide (SiO2)

Serpentinite (Serpentinite (Hydrated magnesium iron phyllosilicate)) — metamorphic

Serpentinite

Serpentinite (Hydrated magnesium iron phyllosilicate)

Quartz Pebble (Silicon Dioxide (SiO2)) — mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Fossiliferous Limestone (Bioclastic Limestone (Calcium Carbonate, CaCO3)) — sedimentary

Fossiliferous Limestone

Bioclastic Limestone (Calcium Carbonate, CaCO3)

Small tumbled dark stone, possibly basalt or slag (Likely fine-grained basalt; exact identification is uncertain from the photograph) — igneous

Small tumbled dark stone, possibly basalt or slag

Likely fine-grained basalt; exact identification is uncertain from the photograph

Fossilized oyster or bivalve shell (Fossil Gryphaeidae or Ostreoidea; calcitic shell, CaCO₃) — fossil

Fossilized oyster or bivalve shell

Fossil Gryphaeidae or Ostreoidea; calcitic shell, CaCO₃

Sandstone (Sedimentary Rock (Quartz Arenite)) — sedimentary

Sandstone

Sedimentary Rock (Quartz Arenite)

Quartz Pebble (Silicon Dioxide (SiO2)) — sedimentary

Quartz Pebble

Silicon Dioxide (SiO2)

Septarian Nodule (Septarian Concretion (Calcite, Aragonite, and Limestone)) — sedimentary

Septarian Nodule

Septarian Concretion (Calcite, Aragonite, and Limestone)

Petoskey Stone (Hexagonaria percarinata) — fossil

Petoskey Stone

Hexagonaria percarinata

Sandstone (Sedimentary Rock (Quartz arenite)) — sedimentary

Sandstone

Sedimentary Rock (Quartz arenite)

Sandstone (Sedimentary Rock (Quartz arenite / Lithic sandstone)) — sedimentary

Sandstone

Sedimentary Rock (Quartz arenite / Lithic sandstone)

Quartz Pebble (Silicon Dioxide (SiO2)) — mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Milky Quartz (Silicon Dioxide (SiO2)) — mineral

Milky Quartz

Silicon Dioxide (SiO2)

Red Jasper (Silicon Dioxide (SiO2) with Iron Oxide inclusions) — sedimentary

Red Jasper

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Quartzite Pebbles with Quartz Veining (SiO2 (Silicon Dioxide with country rock matrix)) — metamorphic

Quartzite Pebbles with Quartz Veining

SiO2 (Silicon Dioxide with country rock matrix)

Quartz Vein in Schist / Gneiss Metamorphic Matrix (Silicon Dioxide (SiO2) in metamorphic schist host rock) — metamorphic

Quartz Vein in Schist / Gneiss Metamorphic Matrix

Silicon Dioxide (SiO2) in metamorphic schist host rock

Olivine (Peridotite / Dunite Pebble) ((Mg,Fe)2SiO4 (Magnesium Iron Silicate)) — mineral

Olivine (Peridotite / Dunite Pebble)

(Mg,Fe)2SiO4 (Magnesium Iron Silicate)

Yellow Quartz Pebble (Citrine Quartz / Iron-stained Quartz) (Silicon Dioxide (SiO2)) — mineral

Yellow Quartz Pebble (Citrine Quartz / Iron-stained Quartz)

Silicon Dioxide (SiO2)