Tiger's Eye
Pseudomorph of quartz after crocidolite (SiO2)
metamorphic
Category
Mineral (Biogenic Replacement)
Browse mineral (biogenic replacement) specimens identified by the Rock Identifier community.
Polished orbicular jasper (likely ocean jasper)
Silicified microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions
gemstone
Fossil Shell
Phylum Mollusca (Bivalvia or Brachiopoda)
fossil
Pyrite
Iron Disulfide (FeS2)
mineral
Chert
Chert (SiO2)
sedimentary
Fossilized Coral (Petoskey Stone or Rugose Coral)
Antophyllum (Hexagonaria) or Scleractinia (CaCO3)
sedimentary
Chert (Flint variety)
Chert (Cryptocrystalline variety of Quartz, SiO2)
sedimentary
Chert (Flint) Pebble
Microcrystalline Quartz (SiO2)
sedimentary
Green Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Chert (Septarian or Banded Nodular Variety)
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Brachiopod
Phylum Brachiopoda (replaced by Calcite/CaCO3)
sedimentary
Polished fossilized ammonite or nautiloid shell
Ammonoidea or Nautiloidea; originally aragonitic shell, commonly replaced by calcite or chalcedony
fossil
Fossil bivalve shell
Likely an extinct or modern-like ribbed cockle/scallop; exact genus requires locality and diagnostic hinge features
fossil
Carnelian
Carnelian (SiO2 with Iron Oxide impurities)
mineral
Pyrite
Iron Disulfide (FeS2)
mineral
Conical fossil shell or shell fragment
Likely a gastropod shell fragment; exact taxon indeterminate from the image
fossil
Jasper
Silicon Dioxide (SiO2)
sedimentary
Banded Jasper
Silicate Mineral (Microcrystalline Quartz / SiO2)
sedimentary
Bivalve Fossil
Bivalvia (Phylum Mollusca)
Fossil
Fossilized Bone / Dinosaur Fossil
Fossilized vertebrate bone (permineralized)
fossil
Likely galena-bearing ore
Galena (lead sulfide, PbS), possibly mixed with quartz or other sulfides
mineral
Metallic sulfide-bearing rock, possibly galena-rich ore
Likely galena (PbS) with iron sulfides and quartz/rock matrix; exact identification requires testing
mineral
Botryoidal Hematite
Hematite (Iron(III) oxide, Fe2O3)
mineral
Tiger's Eye (Pendant)
Quartz Pseudomorph (SiO2) after Crocidolite
mineral
Chalcedony on Matrix
Silicon Dioxide (SiO2)
mineral
Rhodonite
Rhodonite (Manganese Iron Magnesium Calcium Silicate) - (Mn+2,Fe+2,Mg,Ca)SiO3
mineral
Coprolite
Fossilized Feces
fossil
Fossilized Ray Barb (Stinger) Fragment
Myliobatiformes indet. (Fossil stingray spine)
fossil
Calamites (Fossilized Horsetail)
Calamites suckowii (Family: Calamitaceae)
sedimentary
Galena
Galena (lead sulfide, PbS)
mineral
Likely galena-bearing ore
Galena (lead sulfide, PbS), possibly mixed with sulfide minerals
mineral
Jasper Agate
Silicon dioxide (SiO2)
mineral
Chalcedony (Common Opal variant)
Silicon dioxide (SiO2) with varying levels of hydration
mineral
Agated Chert
Microcrystalline Quartz (SiO2)
sedimentary
Fluorite
Calcium fluoride (CaF2)
mineral
Fossil Snail
Gastropoda fossil
fossil
Seashell Fossil
Gastropoda fossil
fossil
Chert (White Chert / Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Nodule)
Silicon Dioxide (SiO2)
sedimentary
Coprolite
Fossilized feces (various taxa)
sedimentary
Chert (Jasper/Carnelian variety)
Microcrystalline Quartz (SiO2)
sedimentary
Jasper
Silicon dioxide (SiO2)
sedimentary