Chert (containing a small fossil)
Microcrystalline Quartz (SiO2)
sedimentary
Category
Marble
Browse marble specimens identified by the Rock Identifier community.
Eclogite
Eclogite (Omphacite-Garnet rock)
metamorphic
Spondylus Oyster Calcification / Fossilized Oyster
Spondylus (Thorny Oyster) / Calcium Carbonate (CaCO3)
sedimentary
Cupronickel (on a 1981 Mexico 20 Pesos coin)
Copper-Nickel Alloy (Cu75Ni25)
mineral
Granite Thin Section
Granitic rock (Phaneritic texture)
igneous
Aragonite
Aragonite (Carbonate mineral), CaCO3
mineral
Kimberlite
Kimberlite (Porphyritic Peridotite)
Igneous
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Pearl
Biogenic CaCO3 (Aragonite)
mineral
Glauconitic Sandstone (Greensand)
Glauconitic Sandstone ((K, Na)(Fe3+, Al, Mg)2(Si, Al)4O10(OH)2)
sedimentary
Pearl
Calcium carbonate (CaCO3) - mainly Aragonite with Conchiolin
mineraloid
Ferruginous Sandstone
Clastic sedimentary rock (primarily SiO2 with Fe2O3 cement)
sedimentary
Ammonite Fossil
Ammonitida (Extinct subclass of Cephalopoda)
sedimentary
Sandstone
Arenite (SiO2 based with quartz grains)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Chert (specifically Flint or Common Opal variant)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Fossilized Shark Tooth
Carcharodon carcharias (fossilized) / Hydroxyapatite permineralized with silica or iron
sedimentary
Aragonite Star Cluster
Aragonite (Calcium Carbonate, CaCO3)
mineral
Fossiliferous Limestone (Crinoidal)
Calcium Carbonate (CaCO3) - Limestone containing bioclasts
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Limestone
Calcareous sedimentary rock (CaCO3)
sedimentary
Fossilized Shark Tooth (Cretaceous to Neogene)
Elasmobranchii dental fossil (likely Squalicorax or similar species)
mineral (biogenic replacement)
Pearl
Calcium Carbonate (primarily Aragonite and Calcite), CaCO3
mineral
Chert with Quartz Veining
Silicon Dioxide (SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Natural or Cultured Pearl
Calcium Carbonate (Aragonite and Conchiolin), CaCO3
Mineral (Organic)
Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Piddock bored rock (Boring Stone)
Ichnofossil-bearing Limestone or Mudstone (trace fossils by Pholadidae)
sedimentary
Spinifex Textured Komatiite
Ultramafic Komatiite (with Olivine Spinifex)
igneous
Green Druzy Quartz (Prasiolite)
Silicon Dioxide (SiO2) with inclusions (typically Chlorite or Actinolite)
mineral
Olivine (Peridot)
Magnesium Iron Silicate (Mg, Fe)2SiO4
mineral
Chalk
Calcium Carbonate (CaCO3)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Limestone
Calcium carbonate (CaCO3)
sedimentary
Sandstone (with potential mineral inclusions)
Clastic sedimentary rock (primarily Quartz, SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Fossilized Horn Coral
Rugosa
fossil
Stromatolite
Biogenic Sedimentary Rock (composed predominantly of CaCO3)
sedimentary
Chert (varieties include Flint and Jasper)
Silicon Dioxide (SiO2)
sedimentary
Chert (specifically Jasper)
Silicon dioxide (SiO2) with iron oxide inclusions
sedimentary
Chert Nodule (Fossiliferous Chert)
Microcrystalline Quartz (SiO2)
sedimentary