ABUNDANCEAND DISTRIBUTION OF PYRITE AND METALS IN I-99 ROADCUTS, CENTRE COUNTY PENNSYLVANIA

A set of 22 samples representing 600 feet of Bald Eagle sandstone in the I-99 roadcut at Skytop was collected and analyzed by ACTLABS for 50 elements. A zone 500 feet long averages 2.3% S, equivalent to 4.3% pyrite. S contents of individual 30-foot intervals range from 0.8 to 4.7% S, indicating the extensive distribution of pyrite on small veinlets as well as a few larger veins. Averages and ranges for other elements in this 500-foot zone are As 7.8 ppm (2.7-18), Cu 11.2 ppm (2-56), Ni 21 ppm (16-44), Pb 167 ppm (5 to 1450) and Zn 135 ppm (16 to 294). The Pb, Zn and As values are highest in and near major vein zones. Iron contents are relatively uniform, showing little correlation with S, suggesting that much of the pyrite in fine veinlets is derived by sulfidization of Fe from the wallrock. Analyses of 3 sulfide concentrates indicate that up to 120 ppm As may occur in the pyrite, though traces of arsenides have been recognized. Co and Sb also appear to occur in the pyrite. Cadmium probably occurs in sphalerite, which is observed along the veins.