VALENCE OF SULFUR IN DISULFIDES - AN OVERLOOKED CLUE TO THE GENESIS OF MISSISSIPPI VALLEY-TYPE LEAD-ZINC DEPOSITS.

The purpose of this note is to draw attention to the problem of the precipitation of pyrite under the conditions of the formation of Mississippi Valley sulfide deposits. The abundance of pyrite and its dimorph, marcasite, varies from major to minor among Mississippi Valley-type deposits; nevertheless, the disulfides are ubiquitous components of Mississippi Valley sulfide deposits. Consequently, identifying the mechanism by which the iron disulfide minerals precipitated will provide clues to the genesis of the deposits. An overlooked aspect of the precipitation of these disulfide minerals is the valence of sulfur in pyrite, marcasite, vaesite, and some other minerals in Mississippi Valley sulfide deposits.