Polished brecciated jasper
Jasper (microcrystalline quartz, SiO₂), likely brecciated and iron-stained
metamorphic
Category
Biogenic Material
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Banded agate (likely carnelian/chalcedony)
Microcrystalline quartz, SiO₂; iron-stained chalcedony
mineral
Granite
Felsic intrusive igneous rock
igneous
Weathered fossiliferous limestone fragment, possibly fossil coral or shell material
Indeterminate carbonate fossil in calcitic limestone; likely composed mainly of calcite (CaCO₃), but species identification is not possible from this image alone
fossil
Smoky quartz (likely)
Quartz, silicon dioxide (SiO₂), naturally irradiated variety
mineral
Slate
Metamorphic Pelitic Rock
metamorphic
Flint (or Chert)
Microcrystalline quartz (SiO2)
sedimentary
Slate
Metamorphic Pelitic Rock
metamorphic
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Chert / Flint
Silicon Dioxide (SiO2)
sedimentary
Granite Cobble
Granite (Phaneritic Igneous Rock)
igneous
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Limestone with Calcite Veins
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Chert (Flint)
Chert (Cryptocrystalline silicon dioxide, SiO2)
sedimentary
Chert (varieties including Flint or Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (variations like Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Ferrochrome Slag
Anthropogenic silicate/oxide glass (Complex silicate matrix with Cr-Fe-Si inclusions)
Industrial byproduct (often confused with igneous rocks or meteorites)
Chert (Flint)
Chert (SiO2)
sedimentary
Diabase
Diabase (also known as Dolerite)
igneous
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Stichtite in Serpentine (Atlantasite)
Mg6Cr2CO3(OH)16·4H2O in Mg3Si2O5(OH)4
metamorphic
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Diamond
Natural Diamond (Carbon, C)
mineral
Chert (Flint)
Chert (Silicon Dioxide, SiO2)
sedimentary
Asphalt (Bituminous Concrete)
Bituminous Concrete / Pavement
man-made (synthetic rock)
Red Sandstone
Arenite (primarily Quartz with Iron Oxide)
sedimentary
Sandstone
Arenite
sedimentary
Banded Calcite (often sold as 'Mexican Onyx')
Calcite (Calcium Carbonate, CaCO3)
Mineral / Sedimentary Rock
Chert (Chalcedony/Agate variety)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Chert / Flint Nodule
Silicon Dioxide (SiO2)
sedimentary
Banded Calcite (Mexican Onyx)
Calcium Carbonate (CaCO3)
sedimentary
Chert (Flint variety)
Silicon Dioxide (SiO2)
sedimentary
Ferruginous Sandstone (with Laterite)
Ferruginous Arenite (FeO(OH)·nH2O)
sedimentary
Diamond (in a gold setting)
Carbon (C)
mineral
Diamond (in jewelry setting)
Cubic Carbon (C)
mineral
Small rounded pebble
Indeterminate lithic grain; likely weathered sandstone, iron-stained quartz-rich rock, or a concretion
sedimentary
Petrified Wood
Silicified Wood (SiO2)
fossil
Chert (and Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Rose quartz
Quartz (silicon dioxide, SiO₂), pink massive variety
mineral