Tufa (Limestone)
Calcareous Tufa (CaCO3)
sedimentary
Category
Organic Gemstone (Not A Mineral)
Browse organic gemstone (not a mineral) specimens identified by the Rock Identifier community.
Learn about Organic Gemstone (Not A Mineral) in the encyclopedia
View all →
Petrified Wood
Silicified wood (Quartz, Chalcedony, or Opal)
sedimentary
Petrified Wood
Silicified wood (Quartz, SiO2)
metamorphic
Chert (Chalcedony)
Silicon Dioxide (SiO2)
sedimentary
Fossil Shark Tooth
Odontaspididae (likely Carcharias sp.)
fossil
Petrified Bone Pebble
Silicified Fossilized Bone
fossil
Fossilized Crab Carapace (Concretion)
Decapoda (fossil), typically preserved in calcite or siderite concretion
sedimentary
Glauconite (Greensand)
(K, Na)(Fe3⁰, Al, Mg)₂(Si, Al)₄O₁₀(OH)₂
sedimentary
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Moqui Marbles
Iron Oxide Concretion (Hematite/Goethite)
sedimentary
Petrified Wood
Silicified wood (primarily SiO2)
sedimentary
Petrified Wood
Silicified wood (primarily SiO2)
metamorphic
Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Fossilized Oyster Shell (Limestone/Coquina)
Crassostrea (Fossilized Bivalve), Calcium Carbonate (CaCO3)
sedimentary
Fossil Shark Tooth
Carcharadon sp. (likely Carcharodon carcharias or similar Lamniformes)
fossil
Green Sandstone
Glauconitic Sandstone
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Moss Agate
Silicon dioxide (SiO2) with inclusions
Mineral
Chert (varietal Flint or Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Olivine (Peridotite)
Magnesium iron silicate (Mg, Fe)2SiO4
igneous
Chert (often called Jasper in this color variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint/Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (specifically Flint or Jasper variant)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Fossilized Tiger Shark Tooth
Galeocerdo cuvier (fossilized hydroxylapatite)
sedimentary
Chert / Flint
Microcrystalline or cryptocrystalline quartz (SiO2)
sedimentary
Chert / Flint
Chert (SiO2)
sedimentary
Shungite
Non-crystalline carbon (allotrope of carbon)
metamorphic
Dendritic Agate / Moss Agate
Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions
mineral
Moss Agate
Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite
mineral
Moss Agate
Chalcedony (Silicon Dioxide, SiO2) with dendritic inclusions
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Amber
Succinite (fossilized resin)
mineral
Moss Agate
Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)
mineral
Amber
Fossilized Tree Resin (C10H16O)
mineral
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert with Quartz/Calcite Vein
Microcrystalline Silica (SiO2)
sedimentary
Bituminous Coal (with Anthracite or Vitrinite inclusion)
Organic-rich Sedimentary Rock (Carboniferous classification)
sedimentary
Fossilized Sand Tiger Shark Tooth
Carcharias taurus / Striatolamia macrota (mineralized as Hydroxylapatite/Francolite)
sedimentary (fossil)
Chert (Chalky/Gray Variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Pyrite in Shale
Iron Disulfide (FeS2)
mineral
Mother of Pearl and Onyx
Aragonite (Mother of Pearl) and Chalcedony (Onyx)
mineral