Amethyst geode fragment
Quartz, SiO₂; purple color from irradiation-related iron impurities
mineral
Category
Synthetic Polymer (Synthetic Material)
Browse synthetic polymer (synthetic material) specimens identified by the Rock Identifier community.
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Tiger's Eye
Quartz pseudomorph after crocidolite (SiO2)
gemstone
Travertine
Calcium Carbonate (CaCO3)
sedimentary
Fossiliferous Flint
Microcrystalline Quartz (SiO2) with Echinoid Fossil
sedimentary
Limpets Shell / Fossil Specimen
Patellogastropoda (Class)
fossil
Chrysocolla in Quartz
Hydrated copper phyllosilicate with silicon dioxide (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O + SiO2)
mineral
Diamond
Carbon (C)
gemstone
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint nodules in Limestone)
Silicon dioxide (SiO2)
sedimentary
Slate
Foliated Metamorphic Rock (composed of quartz, illite, chlorite)
metamorphic
Chert Pebble
Microcrystalline Quartz (SiO2)
sedimentary
Black Obsidian
Amorphous volcanic glass (primarily SiO2)
igneous
Diamond (or Simulant)
Carbon (C) or various simulants (e.g., Cubic Zirconia)
gemstone
Tiger's Eye and Gemstone Assortment
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions)
metamorphic
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Chert Nodule
Microcrystalline Quartz (SiO2)
sedimentary
Diamond
Diamond (C)
mineral
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Chert Pebble
Chert (Silicon Dioxide, SiO2)
sedimentary
Chert / Flint
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint/Jasper variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (specifically Tan/Gray Chert)
Microcrystalline quartz (SiO2)
sedimentary
Jasper (Multi-color Chert)
Silicon Dioxide (SiO2) with impurities
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (variously known as Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint/Jasper)
Silicon dioxide (SiO2) - Microcrystalline quartz
sedimentary
Chert (Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Chert (varietal: Flint/Jasper)
Silicon Dioxide (SiO2)
sedimentary
Kaolinite (Chalky Clay)
Kaolinite (Al2Si2O5(OH)4)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
gemstone
Diamond
Carbon (C)
gemstone
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Concrete with Aggregate
Composite construction material; primary matrix is Calcium Silicate Hydrate (C-S-H)
anthropogenic (human-made) sedimentary-like material
Asphalt Concrete (Bituminous Pavement)
Aggregates in Bitumen Matrix
Technogenic / Anthropogenic Pavement Material
Tumbled chalcedony (likely moss or dendritic agate)
Microcrystalline quartz, SiO₂, with iron-oxide inclusions
mineral
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chalcedony (likely agate/chert variety)
Microcrystalline quartz, SiO₂
mineral
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary