Iolite (Cordierite)
Cordierite (Magnesium Aluminum Silicate), Mg2Al4Si5O18
Mineral
Category
Organic Gemstone (Often Associated With Sedimentary Sequences)
Browse organic gemstone (often associated with sedimentary sequences) specimens identified by the Rock Identifier community.
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Polished brecciated jasper
Jasper, opaque microcrystalline quartz (SiO₂), likely brecciated jasper with iron-oxide and dark silicate inclusions
mineral
Amazonite
Microcline (KAlSi3O8) with lead impurities
mineral
Chert (specifically Gray Chert/Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Sandstone with Algae Growth
Arenite with Chlorophyta/Lichen
sedimentary
Chert (and/or Chalcedony)
Microcrystalline Silica (SiO2)
sedimentary
Chert (often called Flint)
Microcrystalline quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
fossil
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Amazonite
K(AlSi3O8) - Microcline (Lead-bearing variety)
mineral
Shale
Fissile mudrock (composed primarily of clay minerals and quartz)
sedimentary
Yellow Agate
Silicon Dioxide (SiO2) - variety of Chalcedony
mineral
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Goldstone (Synthetic Aventurescence Glass)
Cuprous Aventurescent Glass (Silicon Dioxide with Copper inclusions)
mineraloid / man-made material
Jasper
Silicon Dioxide (Microcrystalline Quartz), SiO2
sedimentary
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Jasper
Silicon Dioxide (SiO2) with impurities
sedimentary
Chert with Iron Inclusions
Microcrystalline Quartz (SiO2) with Hematite/Limonite
sedimentary
Chert Nodule / Ironstone Concretion
Microcrystalline Quartz (SiO2) with Iron Oxides
sedimentary
Microcrystalline Quartz (Chert/Agate)
Silicon Dioxide (SiO2)
sedimentary
Green Jasper
Jasper (Silicates, SiO2)
sedimentary
Chert (Yellow/Brown variety)
Chert (SiO2)
sedimentary
Flint
Chert (SiO2)
sedimentary
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Jasper
Silicon dioxide (SiO2)
Mineral / Sedimentary
Amber
Amber (C10H16O)
mineral
Travertine
Travertine (a terrestrial form of Limestone, CaCO3)
sedimentary
Fuchsite
Chromian Muscovite (K(Al,Cr)2(AlSi3O10)(OH)2)
Mineral
Petrified Wood
Silicified wood (SiO2)
fossil
Limestone with Lichen
Calcium Carbonate (CaCO3) with Endolithic/Epilithic Lichen
sedimentary
Red Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Chrysocolla on Quartz
Chrysocolla (Cu2−xAlx(H2−xSi2O5)(OH)4·nH2O) often associated with Quartz (SiO2)
mineral
Fossilized Bone Fragment
Permineralized Vertebrate Fossil (Hydroxyapatite replaced by Minerals)
sedimentary
Chert (varieties include Flint and Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Fossiliferous Limestone
Biomicrite / Limestone with fossils
sedimentary
Petrified Wood
Silicified Wood (SiO2 - Quartz/Chalcendony replacing organic matter)
sedimentary
Chert (Nodule)
Microcrystalline Quartz (SiO2)
sedimentary
Siltstone with Fossil Cast
Sedimentary Rock (Siltstone / Fine-grained Sandstone)
sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Amber
Succinicum (Organic compound, primarily C10H16O)
Organic Gemstone (Mineraloid)
Petrified Wood
Silicified Wood (SiO2)
fossil