Where is Coal with Pyrite found?
Bituminous Coal with Pyrite (FeS2)
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Open the appCoal with Pyrite occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Coal with Pyrite
Appalachian Basin, USA
Extensive bituminous coal deposits, particularly in states like West Virginia, Pennsylvania, Kentucky, and Ohio, often contain significant pyrite due to marine incursions during the Pennsylvanian period.
Illinois Basin, USA
Coal seams in Illinois, Indiana, and Kentucky are known for their high sulfur content, largely attributed to abundant pyrite.
Ruhr Basin, Germany
Historically significant coal-producing region with Carboniferous bituminous coals, often containing pyrite.
Donbas Basin, Ukraine/Russia
Major coalfield with high-quality bituminous coals, where pyrite is a common accessory mineral.
Bowen Basin, Australia
Permian coal deposits, including coking coals, can contain varying amounts of pyrite.
Collecting tips
- Visual Inspection. Look for distinct brassy yellow, metallic specks, nodules, or bands within the black coal matrix. These can range from microscopic to several centimeters in size.
- Density. Coal with significant pyrite will feel noticeably heavier than pure coal due to pyrite's higher specific gravity (5.0-5.2 g/cm³ vs. coal's 1.2-1.5 g/cm³).
- Hardness Test. Pyrite is much harder than coal (6-6.5 on Mohs scale vs. 2.5-3 for coal). A steel knife will scratch coal but not pyrite.
- Streak Test. Pyrite leaves a greenish-black to brownish-black streak on an unglazed porcelain plate, while coal leaves a black or brownish-black streak.
- Acid Test (Caution!). Dilute hydrochloric acid (HCl) will not react with pyrite, but it can be used to distinguish it from other sulfide minerals if necessary. However, this is generally not needed for identification in coal.
Quick Check
- Color:
- Black (coal) with brassy yellow (pyrite)
- Luster:
- Vitreous to dull (coal) and metallic (pyrite)
- Streak:
- Black to brownish-black (coal) and greenish-black to brownish-black (pyrite)
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