Item Number: SR09

The distribution of pyrite in the Springfield Coal Member (V), Petersburg Formation (Pennsylvanian System), was mapped underground in the Thunderbird Mine in Sullivan County, Ind. Megascopic study of data and samples from some 57 locations within the mine revealed that extreme fluctuations in the distribution of physical forms of pyrite exist. Coal in topographically high areas of a coal seam is generally thinner and contains a higher pyrite concentration. Massive lenticular pyrite occurs mainly within the upper 6 inches of the coal seam or directly below an inorganic sediment parting. Total pyrite of all forms appears to have a slightly higher concentration in the lower third of the seam. Major cleats filled with pyrite appear to be more abundant in topographically high areas. Minor cleats filled with pyrite do not seem to have any particular pattern of distribution or preference of location. Microscopic study of four master channel samples showed that 42 percent of the pyrite is lenticular and is mainly associated with vitrinite and exinite coal macerals and with inorganic partings (mostly clay). Although clay and silt constitute more than 15 percent of the total coal seam in only a few places, as much as 47 percent of the total pyrite in the seam may be associated with them. Pyrite crystal size and purity have a wide range and variation. Some 20 representative samples of pyrite, when studied in greater detail, showed crystal sizes ranging from 1 micron to more than 60 microns. Pyrite of museum-grade purite is rare. An electrographic analysis study of the 20 petrographic samples showed that the rate of oxidation of pyrite is inversely related to its crystallinity, crystal size, and purity. X-ray analysis of these samples tended to substantiate these conditions.

Khawaja, I. U., 1975, Pyrite in the Springfield Coal Member (V), Petersburg Formation, Sullivan County, Indiana: Indiana Geological Survey Special Report 09, 24 p., 1 pl., 15 figs. doi: 10.5967/pgc8-1e29

You may also like:

Keywords: pyrite, Pennsylvanian, petrology, Springfield Coal Member, Petersburg Formation, mineral

Can't find what you're looking for? Feel free to contact us directly:

Indiana Geological and Water Survey
1001 E. 10th St.
Bloomington, IN 47405
812-855-7636 (phone)
812-855-2862 (fax)

IGS Return Policy

  • Original sales receipt required.
  • Returns accepted within 30 days of purchase date.
  • Refund will be issued by the same method of payment as purchased.
  • Products must be returned in the same new condition as purchased.
  • Refunds on custom orders and digital products are NOT allowed.
  • Customers are responsible for paying shipping costs to return products.

Updated 8/19/2020