Chert (Commonly known as Flint)
Microcrystalline Quartz (SiO2)
Category
Browse sedimentary (with some aspects of mineral replacement) specimens identified by the Rock Identifier community.
Chert (Commonly known as Flint)
Microcrystalline Quartz (SiO2)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Petrified Wood
Silicon Dioxide (SiO2) - Calcified / Silicified Wood
Chalcedony (specifically Agate or Water-worn Quartzite)
Silicon Dioxide (SiO2)
Fossilized Coral
Cnidaria fossil / Calcite-replaced coral
Chert (Flint) Nodule
Microcrystalline Quartz (SiO2)
Flint (Chert Nodule)
Microcrystalline Quartz (SiO2)
Flint
Silicon Dioxide (SiO2) - Chert variety
Chert (Flint) with Limestone Coating
Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3) cortex
Amber Chert (Jasper)
Microcrystalline Quartz (SiO2)
Chert
Microcrystalline Quartz (SiO2)
Chert (Flint)
Chert (SiO2)
Chert (specifically Flint or Common Opal/Chalcedony mix)
Microcrystalline Quartz (SiO2)
Flint
Silicon Dioxide (SiO2)
Chert (Pebble)
Silicon Dioxide (SiO2)
Chert (Flint/Nodule)
Silicon Dioxide (SiO2)
Flint
Microcrystalline Quartz (SiO2)
Flint
Silicon dioxide (SiO2) - cryptocrystalline quartz
Flint Pebble
Silicon Dioxide (Microcrystalline Quartz, SiO2)
Chert / Flint Arrowheads and Artifacts
Cryptocrystalline quartz (SiO2)
Flint
Microcrystalline quartz (SiO2)
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Flint
Chert (Silicon dioxide, SiO2)
Brachiopod Fossil
Phylum Brachiopoda (replaced by Calcite or Silica)
Chert (with Quartz)
Microcrystalline Quartz (SiO2)
Chert (Arrowhead variety)
Chert (SiO2)
Chert (Flint)
Chert (SiO2)
Flint or Chert
Microcrystalline Quartz (SiO2)
Feldspar
KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8
Gneiss (specifically Epidote-Quartz Gneiss)
Gneiss containing Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)) and Quartz (SiO2)
Selenite (variety of Gypsum)
Calcium sulfate dihydrate (CaSO4·2H2O)
Vesicular basalt (weathered volcanic scoria)
Basalt, predominantly plagioclase feldspar and clinopyroxene with possible olivine; vesicular texture
Goethite-rich ironstone
Goethite, α-FeO(OH), likely with limonite and other iron oxides
Magnetite (Iron Ore)
Magnetite (Fe3O4)
Chert
Chert (Microcrystalline Quartz, SiO2)
Quartz pebble
Silicon dioxide (SiO2)
Fossil coral fragment
Likely colonial scleractinian coral; calcite/aragonite (CaCO₃)
Pyrite-rich rock (iron pyrite specimen)
Pyrite, FeS₂, likely in a sulfide-rich matrix
Celestite (Celestine)
Strontium sulfate (SrSO4)
Gneiss
Metamorphic Gneiss (High-grade regional metamorphism)
Quartz Geode
Silicon Dioxide (SiO2)
Pyrite
Iron Sulfide (FeS2)