Rock (Likely Sedimentary)

Browse rock (likely sedimentary) specimens identified by the Rock Identifier community.

Coal (specifically Bituminous or Anthracite)

Organic sedimentary rock; primarily Carbon (C) with varying H, S, O, N

sedimentary

Sandstone Cobble with Liesegang Rings

Arenite with iron oxide precipitation (SiO2 matrix with Fe2O3 banding)

sedimentary

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

sedimentary

Gossan with Copper Carbonate (Chrysocolla/Malachite)

Ferruginous Oxide (Gossan) with Cu2CO3(OH)2 (Malachite) or (Cu,Al)2H2Si2O5(OH)4 (Chrysocolla)

Mineral/Sedimentary Interface

Limestone

Calcium Carbonate (CaCO3)

sedimentary

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

mineral

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

mineral

Red Jasper

Jasper (Silicon Dioxide, SiO2 with Fe2O3 inclusions)

mineral

Basalt with Caliche Crust

Aphanitic Mafic Igneous Rock with Calcium Carbonate (CaCO3) coating

igneous

Jasper River Pebble

Silicon Dioxide (SiO2)

sedimentary (microcrystalline quartz)

River/Stream Pebble

Clast / Detrital Grain / Rounded Sedimentary Particle (Compositionally variable, commonly Quartz, Feldspar, Chert, or other resistant rock fragments)

Mineral, specifically a rock fragment

Jasper (likely a variety of Yellow or Mustard Jasper)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

sedimentary (chemically precipitated mineral)

Jasper and Quartzite mix

Silicon Dioxide (SiO2) with impurities

sedimentary or metamorphic

Slate with Red Sandstone Landscaping Rock

Foliated Pelitic Metamorphic Rock (Slate) and Ferruginous Sandstone

metamorphic and sedimentary

Jasper with Quartz inclusions

Silicon Dioxide (SiO2) with varying mineral impurities

sedimentary

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix

Metamorphic or Igneous (context dependent)

Bauxite

Alumina-rich rock (consisting of Gibbsite, Boehmite, and Diaspore)

sedimentary

Chert / Pink Chert

Silicon Dioxide (SiO2)

sedimentary

Conglomerate

Conglomerate (lithified rudite)

sedimentary

Biotite Mica

Biotite, K(Mg,Fe)3AlSi3O10(F,OH)2

mineral

Red Jasper

Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions

sedimentary

Zebra Rock / Zebra Marble

Banded Limestone-Marble Transition

metamorphic

Graywacke (River Cobble)

Graywacke (Lithic Sandstone)

sedimentary

Carnelian

Carnelian (a variety of Chalcedony, SiO₂)

Mineral

Amethyst Geode/Cluster

Quartz (SiO2) - variety Amethyst

Mineral

Desert Rose (Gypsum Variety)

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

mineral

Gneiss

Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Mica/Amphibole)

metamorphic

Gneiss

Gneiss (High-grade regional metamorphic rock)

metamorphic

Anthracite Coal

Anthracite (Carbon-based organic sedimentary rock transitioned to metamorphic)

metamorphic

Chert / Flint

Chert (varieties include Flint)

Sedimentary

Quartz (Druzy Quartz)

Silicon Dioxide (SiO2)

mineral

Red Jasper or Chert

Jasper (SiO2, a variety of chalcedony with iron oxide impurities), Chert (SiO2)

sedimentary

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) within Sedimentary or Igneous Matrix

igneous

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

mineral

Granite Gneiss

Gneiss (derived from granitic protolith)

metamorphic

Carnelian

Chalcedony (cryptocrystalline quartz), SiO2

Mineral

Dolomite on Prehnite (Saddle-shaped Dolomite)

Dolomite [CaMg(CO3)2] on Prehnite [Ca2Al(AlSi3O10)(OH)2]

mineral

Red Jasper (Opaque Chalcedony)

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

sedimentary

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Mineral

Pyrite

Pyrite (FeS2)

Mineral

Graphite

Graphite (Carbon, C)

Mineral

Granite Gneiss

High-grade regional metamorphic rock (Quartz-Feldspar Gneiss)

metamorphic