Chert (Common Opal/Agate mixture)
Microcrystalline Quartz (SiO2)
sedimentary
Category
Metamorphic Or Sedimentary Depending On Local Grade
Browse metamorphic or sedimentary depending on local grade specimens identified by the Rock Identifier community.
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Conglomerate
Clastic Sedimentary Rock
sedimentary
Pearl and Garnet Glass
Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass
mineral and glass
Jadeite Jade
Jadeite (NaAlSi2O6)
metamorphic
Green Aventurine (Fuchsite-bearing Quartz)
Silicon Dioxide with Chromium-rich Muscovite (SiO2 + K(Al,Cr)2(AlSi3O10)(OH)2)
metamorphic
Conglomerate
Conglomeratic Sandstone
sedimentary
Blue Apatite
Apatite (Group), Ca5(PO4)3(F,Cl,OH)
mineral
Anthracite Coal
Anthracite
metamorphic
Coal (Bituminous)
Bituminous Coal (C)
sedimentary
Schist (Oxidized)
Mica Schist with Iron Oxide staining
metamorphic
Caribbean Calcite
Calcium Carbonate (CaCO3) with Aragonite
mineral
Ruby
Corundum (Al2O3 with Chromium traces)
mineral
Quartz with Iron Stains
Quartz (SiO2) with iron oxide/hydroxide staining
Mineral
Yellow Chalcedony
Chalcedony (a cryptocrystalline variety of Quartz, SiO₂)
Mineral
Amethyst
Quartz (SiO2) variety
Mineral
Druzy Quartz
Silicon Dioxide (SiO2)
mineral
Anthracite Coal
Anthracite
sedimentary
Red Jasper (Chert)
Silicon dioxide (SiO2) with iron oxide inclusions
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Jasper with Chert
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Travertine
Calcium Carbonate (CaCO3)
sedimentary
Kambaba Jasper
Rhyolite (Volcanic rock) or Stromatolite (debated)
Igneous/Sedimentary (debated)
Rough Sapphire (Corundum)
Corundum (Al2O3)
mineral
Black Diamond / Black Sapphire
Carbon (C) or Corundum (Al2O3)
mineral
Stichtite in Serpentine (Atlantasite)
Mg6Cr2CO3(OH)16·4H2O in Mg3Si2O5(OH)4
metamorphic
Quartzite Pebbles
Quartzite (primarily SiO2)
metamorphic
Marble
Recrystallized Calcite (CaCO3) Rock
metamorphic
Ocean Jasper
Orbicular Jasper (Silicon Dioxide, SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Hag Stone
Porous sedimentary rock (typically Flint, Chert, or Sandstone) with naturally occurring holes
sedimentary
Quartz Geode
Crystalline Silicon Dioxide (SiO2) in Geode form
sedimentary
Quartz Calcite Vug in Limestone
Calcium Carbonate (CaCO3) with Silicon Dioxide (SiO2) inclusions
sedimentary
Fossil Shark Teeth (likely Sand Tiger Shark)
Carcharias taurus (fossilized dentition)
fossil
Garnet (likely Almandine, Pyrope, or a blend)
Garnet group minerals: X3Y2(SiO4)3, where X and Y represent various metal ions (e.g., Almandine: Fe3Al2(SiO4)3, Pyrope: Mg3Al2(SiO4)3)
Mineral
Quartz (likely)
Quartz (SiO2 - Silicon Dioxide)
Mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Chalcedony (Carnelian Agate pebble)
Silicon Dioxide (SiO2)
mineral
Chalcedony (Commonly known as Carnelian or Agate pebble)
Microcrystalline Quartz (SiO2)
mineral
Carnelian Agate
Silicon Dioxide (SiO2) - variety of Chalcedony
mineral
Quartz Pebble (Geode-like)
Silicon Dioxide (SiO2)
Mineral
Quartz (Chert/Chalcedony variety)
Silicon Dioxide (SiO2)
mineral
Sandstone
Arenite (primarily SiO2)
sedimentary