Black pyrite formation

Figure 4 Sulfur isotope summary for black shales from the Pierre Shale of the Cretaceous Western Interior, North America (Gautier, 1986, 1987), and the Jurassic Posidonienschiefer and Jet Rock (Raiswell et al., 1993). For comparison, the maximum fractionation observed in the Posidonienschiefer by Fisher and Hudson (1987) is also shown. The isotopically uniform and strongly S-depleted pyrites of the Jurassic shales and the Cretaceous Sharon Springs Member of the Pierre Shale—like the sediments of the modern Black Sea and Cariaco Basin (Figure 7)—are diagnostic of euxinic (water-column) pyrite formation (see Section 7.06.3.4.2). By contrast, the Cretaceous Gammon Shale shows the S enrichments and broad range of 6 S values possible under oxic depositional conditions (Gautier, 1986, 1987).

Calvert S. E., Thode H. G., Yeung D., and Karlin R. E. (1996) A stable isotope study of pyrite formation in the late Pleistocene and Holocene sediments of the Black Sea. Geochim. Cosmochim. Acta 60, 1261-1270. 

Extraction.—(1) From Pyrites.—In the oxidation of the pyrites (or other sulphur mineral) for the formation of sulphur dioxide in the manufacture of sulphuric acid, foreign elements like arsenic and selenium also undergo oxidation and pass ofC as vapours with the sulphur dioxide. The selenium dioxide produced in this manner their suffers more or less complete reduction by the sulphur dioxide, when finely divided selenium separates, mainly in the lead chambers, as a red, amorphous powder, accompanied possibly by some of the greyish-black form a portion of the dioxide is also found in the Glover tower acid. The amount of selenium in the chamber mud depends, of course, on the nature of the pyrites relatively large quantities of compounds of arsenic, zinc, tin, lead, iron, copper or mercury are always present, arising almost entirely from impurities in the pyrites. 

In eastern Kentucky the Ohio Shale terminology has been used where the Mississippian Sunbury Shale and the underlying Bedford Shale can still be recognized. A typical stratigraphic section with carbon distribution is shown in Figure 3. Typically the overburden is a mixture of claystone and siltstone in the Borden Formation. This unit directly overlies the Sunbury Shale which is a black, laminated, siliceous shale rich in organic matter with some pyrite. The Sunbury thins to the south from 20-25 feet in Lewis County to four feet in Estill County. 

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