Limestone
Calcium Carbonate (CaCO3)
sedimentary
Category
Organic Mineraloid
Browse organic mineraloid specimens identified by the Rock Identifier community.
Learn about Organic Mineraloid in the encyclopedia
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Turquoise and Red Coral
Turquoise: CuAl6(PO4)4(OH)8·4H2O; Red Coral: Corallium rubrum (organic gemstone)
mineral
Amber
Fossilized Tree Resin (C10H16O)
gemstone
Chert Nodule
Microcrystalline Quartz (SiO2)
sedimentary
Freshwater Pearl
Calcium Carbonate (CaCO3) in the form of Aragonite and Calcite
gemstone
Amber (Rough)
Amber (Fossilized Tree Resin, succinite)
mineral
Moss Agate
Cryptocrystalline Quartz (SiO2 with Manganese or Iron Oxide inclusions)
mineral
Chert (specifically Blue Chert or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Pink Opal (Common Opal)
Amorphous Hydrated Silica (SiO2·nH2O)
mineral
Black Onyx
Cryptocrystalline Quartz (SiO2 with organic/iron impurities)
mineral
Blue Agate (Tumbled and Dyed)
Silicon Dioxide (SiO2) with likely organic dyes
mineral
Plume Agate
Silicon Dioxide (SiO2) - Chalcedony Variety
mineral
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Moss agate bracelet
Chalcedony (microcrystalline quartz, SiO₂) with chlorite/amphibole inclusions
gemstone
Fossil gastropod shell
Fossilized marine gastropod; exact genus/species requires locality and examination
fossil
Chert Nodule in Limestone (Flint in Chalk)
SiO2 (Microcrystalline Quartz) in CaCO3 (Calcite)
sedimentary
Banded Agate (Dyed)
SiO2 (Silicon Dioxide / Microcrystalline Quartz)
mineral
Tumbled chert or flint pebble
Microcrystalline quartz (SiO₂), likely chert; exact variety uncertain from the image
sedimentary
Moss Agate
Silicon Dioxide (SiO2) with inclusions
mineral
Amber (Rough)
Succinite (Resinite)
gemstone
Pink Opal
Hydrated Silica (SiO2·nH2O) with Palygorskite/Sepiolite inclusions
gemstone
Petrified Wood
Silicified Wood (SiO2)
metamorphic
Petrified Wood
Silicified wood (primarily SiO2 - Silicon Dioxide/Quartz)
metamorphic
Gastropod Steinkern (Fossil Snail Internal Mold)
Class Gastropoda (Internal Mold)
sedimentary
Moss Agate
Chalcedony (SiO2) with inclusions of manganese or iron oxides
mineral
Tufa (Limestone)
Calcareous Tufa (CaCO3)
sedimentary
Moss Agate
Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)
Mineral
Amber Inlay Jewelry
Fossilized Resin (C10H16O)
Organic Gemstone (Biogenic)
Sandstone with Trace Fossils
Quartz Arenite with Bioturbation (Trace Fossils)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Vivianite
Vivianite, Fe2+3(PO4)2·8H2O
mineral
Fossilized Coral (Petoskey Stone or Tabulate Coral)
Scleractinia or Tabulata (CaCO3 - Calcium Carbonate)
fossil
Pyrite in Slate
Iron Sulfide (FeS2) in Slate host matrix
metamorphic
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Fossil Shark Tooth
Elasmobranchii tooth fossil (e.g., Otodus / Carcharocles)
fossil
Ironstone Concretion (Moqui Marble / Boji Stone)
Sedimentary Iron Oxide Concretion (Fe2O3 / FeO(OH))
sedimentary
Limestone with Fossil Inclusions
Sedimentary Carbonate Rock (CaCO3)
sedimentary
Jasper
Silicon Dioxide (Microcrystalline Quartz, SiO2)
sedimentary
Jasper
Silicon Dioxide (Microcrystalline Quartz, SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Bivalve Fossil (Brachiopod or Scallop)
Class Bivalvia (or potentially Phylum Brachiopoda)
fossil
Moqui Marble (Shaman Stone)
Ironstone Concretion (Goethite/Hematite Shell)
sedimentary