Starfish Fossil
Asteroidea fossil
fossil
Category
Organic Gemstone (Not A Rock Or Mineral In The Traditional Sense, But Bio Mineralized Material)
Browse organic gemstone (not a rock or mineral in the traditional sense, but bio mineralized material) specimens identified by the Rock Identifier community.
Learn about Organic Gemstone (Not A Rock Or Mineral In The Traditional Sense, But Bio Mineralized Material) in the encyclopedia
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Sandstone
Arenite (primarily SiO2)
sedimentary
Weathered agate or chalcedony nodule
Microcrystalline quartz (SiO₂), likely agate/chalcedony with iron-oxide staining
mineral
Amethyst
Silicon Dioxide with Iron impurities (SiO2)
mineral
Fossilized Shark Tooth
Chondrichthyes (Class)
fossil
Amber
Succinite (Resinite)
Organic Crystal (Mineraloid)
Rose Quartz
Silicon Dioxide (SiO2)
mineral
Amber (possibly a small polished amber cabochon)
Fossilized tree resin; amber is an organic gemstone, not a mineral
gemstone
Weathered mineralized rock fragment
Indeterminate; likely quartz–feldspar-rich lithic material with iron-oxide staining
mineral
Amber
(C10H16O)n – an amorphous organic substance, primarily composed of polymerized isoprenoids.
Mineral
Petrified Wood
Silicified Wood (SiO2)
fossil
Sandstone
Arenite
sedimentary
Amber
Succinite (specifically for Baltic amber); approximate formula C10H16O
organic mineraloid
Fossilized Shark Tooth
Chondrichthyes (Class) fossilized tooth
fossil
Amber
Succinite (Organic Mineraloid)
mineral
Fossil Shark Tooth
Selachii (fossilized dentition)
fossil
Petrified Wood
Silicified wood / Permineralized wood (SiO2)
fossil
Petrified Wood
Silicified Wood (primarily Chalcedony/Quartz, SiO2)
fossil
Fossilized Bone
Permineralized Bone (Vertebrate Fossil)
fossil
Amethyst crystal cluster
Amethyst, purple variety of quartz (SiO₂)
mineral
Petrified Wood
Silicified Wood (SiO2)
fossil
Quartz-rich breccia or iron-stained quartz
Microcrystalline to crystalline quartz (SiO₂), with probable iron-oxide staining and minor host-rock fragments
mineral
Clear Quartz
Silicon Dioxide (SiO2)
mineral
Rose Quartz
Silicon Dioxide (SiO2)
mineral
Concrete or asphalt-like aggregate surface with a dark fragment
Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock
sedimentary
Fossilized bivalve shell fragment
Calcitic fossil shell, likely a pectinid or related bivalve; CaCO₃
fossil
Fossil gastropod shell
Calcareous mollusk shell, chiefly aragonite or calcite (likely a large marine gastropod)
fossil
Smoky Quartz
SiO2 (Silicon Dioxide)
mineral
Quartz-bearing iron-stained breccia
Brecciated quartz/quartzite with iron oxides, chiefly SiO₂ with hematite/goethite and possible feldspar or host-rock fragments
mineral
Ruby
Corundum (Al2O3:Cr)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Sandstone
Arenicola (comprising mostly Quartz, SiO2)
sedimentary
Iron-rich ochre (red/brown hematite pigment)
Hematite, Fe₂O₃, likely mixed with clay and quartz grains
mineral
Clear Quartz
Silicon Dioxide (SiO2)
mineral
Clear Quartz
Silicon Dioxide (SiO2)
mineral
Fossilized Bone
Petrified Bone (Fluorapatite / Calcium Phosphate replacement)
fossil
Limonite (Iron Ore)
Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)
Mineral
Pearl strand
Nacreous pearl, primarily aragonite (CaCO₃) with conchiolin protein
gemstone
Chert (Jasper/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Green Opal
Hydrated amorphous silica (SiO2·nH2O)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Rough emerald specimens
Beryl, Be₃Al₂Si₆O₁₈, colored green by chromium and/or vanadium
gemstone