Formula: Mixture of pyrophillite and sericite.
Description: Pipestone is a compact pink to red metamorphosed mudstone (or argillite) of a consistency that allows it to be carved into pipes and other art objects. It is found as thin layers interbedded with quartzite at several places in Wisconsin. Pipestone has substantial religious significance to Native Americans and the small hand-worked quarries where it is obtained are considered sacred ground. For this reason, no detailed localities will be given.
BARRON COUNTY: A number of small pipestone quarries worked by Native Americans are found in the Blue Hills, northwest of Cameron. Dott and Dalziel (1972) suggest the major mineral in this pipestone is diaspor but X-Ray studies by Gunderson (1983) show that the pipestone is a mixture of kaolinite, muscovite, anatase, hematite and quartz.
MARATHON COUNTY: An argillite, likely a metamorphosed pipestone, has been reported from a quarry on Rib Mountain by Gunderson (1983). X-Ray analysis done by Gunderson find that the rock consists mostly of quartz, kaolinite, pyrophyllite and andalusite.
SAUK COUNTY: Pipestone is found in the Devil’s Lake area near Baraboo. The pipestone is an argillite showing foliation and crenulation. It consists mostly of pyrophyllite, rutile, hematite and quartz (Gunderson, 1986). Woodman (1882) describes this material as quarried from small borrow pits and having an unusual texture with “gray, black, yellow and red veining being intermixed in the same specimen, producing the appearance of some marbles”.
SAWYER COUNTY: An argillite from the Radisson area having the properties of pipestone was found to consist of a mixture of quartz, kaolinite and pyrophyllite (Gunderson, 1986).