This rock is well-exposed in the quarries in NW SW NE Sec. Silicification of Prairie du Chien group rocks is widespread in the Upper Mississippi Valley zinc-lead district where it is prevalent along faults and fractures. This forms massive jasperoid as well as drusy crystals. 28 and SW Sec. Quartz is the major component of the Sunday quartzite throughout the Penokee Range.
Some localities are in Sec.
33 and 34 T.45N. R.1W at Tyler's Fork, in Sec. Some localities are SW corner Sec. T.23N. R.5W. 3 miles west of Alma Center, and at Stanley Mound SW SE Sec. T.23N. R.4W. about 2 km. Quartz is the major component of the quartzite at Necedah Bluff, well exposed in the quarries in NE Sec.