Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Category
Biogenic Material
Browse biogenic material specimens identified by the Rock Identifier community.
Learn about Biogenic Material in the encyclopedia
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Orbicular Granite (specifically Mustard or Yellow Tonalite/Granodiorite)
Orbicular Quartz Diorite / Tonalite
igneous
Limestone (Weathered)
Sedimentary Carbonate Rock (CaCO3)
sedimentary
Red jasper-like chalcedony pebble
Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper
mineral
Asphalt Chunk
Asphalt concrete
man-made composite
Chert (or possibly Flint)
SiO2 (Silicon Dioxide)
Sedimentary Rock
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Garnet Schist
Garnetiferous Mica Schist
metamorphic
Sandstone
Arenite (primarily SiO2)
sedimentary
Coquina or Fossiliferous Limestone
Fossiliferous Calcarenite (CaCO3)
sedimentary
Jasper / Chert (Red)
Cryptocrystalline quartz (SiO2)
Sedimentary / Mineral
Fossil bivalve shell
Likely an extinct or modern-like ribbed cockle/scallop; exact genus requires locality and diagnostic hinge features
fossil
Coquina
Bioclastic Limestone
sedimentary
Sandstone
Arenite (primarily SiO2 with Fe2O3)
sedimentary
Vesicular volcanic rock, likely weathered pumice or scoria
Pumice/scoria; predominantly volcanic glass and feldspar, with possible iron oxides
igneous
Banded Calcite (often sold as Mexican Onyx or Aragonite)
Calcite/Aragonite (Calcium Carbonate, CaCO3)
sedimentary
N/A - Image does not contain a rock or mineral
Anthropogenic textile material
Non-geological
Ferrochrome Slag
Calcium-Aluminium-Magnesium Silicate Slag
industrial byproduct
Engineer Quartz/Quartzite
SiO2 (Silicon Dioxide with binders)
Sedimentary or metamorphic-derived
Cubic Zirconia
Zirconium dioxide (ZrO2)
mineral
Petrified Wood (Jet or Coalified Wood appearance)
Silicified wood (principally SiO2) or Carbonized Wood
sedimentary
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)
sedimentary
Rough amethyst-bearing quartz specimens
Quartz, SiO₂; purple coloration from trace iron and irradiation
mineral
Rhyolitic Tuff
Rhyolitic Tuff / Pyroclastic rock
igneous
Polished Mexican “Crazy Lace” agate tower
Microcrystalline quartz (chalcedony), SiO₂, with iron-oxide inclusions
mineral
Polished green-and-white stone, likely serpentine or nephrite jade
Serpentine-group minerals, commonly antigorite/lizardite; possible nephrite (interlocking actinolite–tremolite)
metamorphic
Vesicular volcanic rock, likely scoria
Scoria; composition commonly basaltic to andesitic, rich in plagioclase and pyroxene
igneous
Gravel / Crushed Stone
Aggregate (mixed mineral rock fragments)
sedimentary
Serpentine
Hydrous magnesium iron silicate, (Mg,Fe)3Si2O5(OH)4
metamorphic
Limestone
Calcite (CaCO3)
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Diamond (or Simulant)
Carbon (C) or relevant simulant formula (e.g., ZrO2 for Cubic Zirconia)
gemstone
Likely basalt pebble
Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine
igneous
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Pink Quartzite
Quartzite (principally Silicon Dioxide, SiO2)
metamorphic
Laterite (Iron-rich bauxite or Gossan)
Ferricrete (Fe2O3·nH2O)
sedimentary
Banded Iron Formation (BIF) with potential Stromatolite/Biogenic Trace
Ferruginous Chert / Banded Iron Formation (BIF)
sedimentary
Tumbled or rough turquoise-like specimen
Turquoise, hydrated copper aluminum phosphate — CuAl₆(PO₄)₄(OH)₈·4H₂O; identification is uncertain from the image
mineral
Beads (likely glass or man-made material)
N/A (artificial material)
Man-made material, not a natural rock or mineral specimen
Note on Image Identification: Textile
N/A (Anthropogenic material)
not a rock
Nephrite Jade
Nephrite
Mineral/Rock
Brecciated jasper/chert
Microcrystalline quartz (SiO₂), with iron-oxide and clay inclusions
sedimentary