Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
metamorphic
Category
Organic Gemstone (Often Associated With Sedimentary Sequences)
Browse organic gemstone (often associated with sedimentary sequences) specimens identified by the Rock Identifier community.
Learn about Organic Gemstone (Often Associated With Sedimentary Sequences) in the encyclopedia
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Fossilized Coral (Petoskey Stone or Rugose Coral)
Antophyllum (Hexagonaria) or Scleractinia (CaCO3)
sedimentary
Dyed Coral
Calcium carbonate (CaCO3) - Calcite or Aragonite with dye
organic gemstone
Chert (variations include Flint/Novaculite)
Chert (formula: SiO2)
sedimentary
Banded Chert
Sedimentary Cryptocrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, formula: SiO2)
sedimentary
Chert (specifically Flint or Gray Chert)
Silicon Dioxide (Microcrystalline Quartz), SiO2
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Desert Rose Fragment (Atypical) / Weathered Chert
Silicon Dioxide (SiO2) or Barium Sulfate (BaSO4) depending on exact mineralogy
sedimentary
Fossiliferous Limestone
Biogenic Sedimentary Rock (CaCO3)
sedimentary
Moonstone (bead form)
Potassium Aluminum Silicate (KAlSi3O8) - a variety of Orthoclase Feldspar
Mineral
Mixed Quartz and Jasper Pebbles
Silicon Dioxide (SiO2)
Mineral
Shale (possibly Carbonaceous or Oil Shale)
Argillaceous Sedimentary Rock
sedimentary
Quartz
Silicon Dioxide (SiO2)
mineral
Natural White Pearl
Calcium Carbonate (Aragonite/Calcite) with Conchiolin - CaCO3
mineraloid
Quartz (Smoky Quartz)
Silicon Dioxide (SiO2)
mineral
Unakite
Altered Granite (Epidote, Pink Orthoclase Feldspar, and Quartz)
metamorphic
Red Jasper with Fossils
Silicified Fossiliferous Jasper (Chert variant, SiO2)
sedimentary
Chert (Nodule)
Chert (primarily Microcrystalline Quartz - SiO2)
sedimentary
Epidote with quartz/feldspar
Epidote, Ca2(Al,Fe)3(SiO4)3(OH)
metamorphic
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Amazonite
K(AlSi3O8) - Lead-bearing Microcline (Tectosilicate)
mineral
Glauconitic Sandstone
Glauconitic Sandstone with high Glauconite concentration ((K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
sedimentary
Rhodochrosite with Quartz
Manganese Carbonate (MnCO3) with Silicon Dioxide (SiO2)
mineral
Chert (Jasper/Agate)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Glauconitic Sandstone
Glauconitic arenite (contains (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
sedimentary
Chert (Green Chert)
Microcrystalline silica (SiO2)
sedimentary
Amber
Succinicum (Succinite); C10H16O
Mineraloid (Organic)
Chert (Common Opal/Agate variety)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Chalcedony/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Red Jasper
Silicon Dioxide (Microcrystalline Quartz) - $SiO_2$
sedimentary
Fluorite
Calcium fluoride, CaF2
Mineral
Lapis Lazuli
Rock composed mainly of lazurite, calcite, and pyrite
gemstone
Lapis Lazuli
Complex silicate rock containing lazurite, pyrite, and calcite
gemstone
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Pink Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Nodule)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Unakite (Epidotized Granite)
Epidotized Granite (SiO2 with Ca2(Al,Fe)3(SiO4)3(OH))
metamorphic
Chert (Jasper variation)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Serpentine
(Mg,Fe)3Si2O5(OH)4
metamorphic