Sphalerite in the Arbuckle dolomite of western Kansas was described by the writer in 1948. (1) Continued drilling has established two areas of sphalerite and possible jasperoid-type chertification in Upper Arbuckle dolomite, at depths below surface of from 4,900 to 6,440 feet.The deepest sphalerite mineralization, previously known in the Mississippi Valley, ranges from the surface to about 1,000 feet in depth in the Southeast Missouri Lead Belt, and to less than one-half that depth in the Tri-State Mining District and the Mississippi Valley Mineral Belt.The largest area, surrounding the Texas Company No. 1 Seal, is 325, 300, and 260 miles from the Tri-State Mining District, the Butterly sphalerite deposit at Davis, Oklahoma, and the Front Range of Colorado, respectively.Sphalerite is found in the Jefferson City-Cotter member and none is found below. It appears to be accompanied by a dark, bluish gray chert, similar to the jasperoid of the Tri-State Mining District. Elliptical areas of mineralization are suggested, the largest having a long axis of 42 miles and a short axis of 22 miles. These appear related to northeast-southwest trending, enechelon, anticlinal folds, crossed by N52E regional structural controls, probably lines of shear.The connection of Seal area sphalerite mineralization with deeper seated intrusives is suggested by the fact that the Seal pattern covers an area of outstanding magnetic and gravity anomalies, believed to reflect basic and acidic intrusives.