Catlinite

Catlinite (also called pipestone) is a type of argillite (metamorphosed mudstone), usually brownish-red in color, which occurs in a matrix of Sioux Quartzite. Because it is fine-grained and easily worked, it is prized by Native Americans, primarily those of the Plains nations for use in making ceremonial pipes such as chanunpas. Pipestone quarries are located and preserved in Pipestone National Monument outside Pipestone, Minnesota, in Pipestone County, Minnesota, and at the Pipestone River in Ontario, Canada.

The term Catlinite came into use after the American painter George Catlin visited the quarries in Minnesota in 1835; but it was Philander Prescott who first wrote about the rock in 1832, noting that evidence indicated that American Indians had been using the quarries since at least as far back as 1637.

Minnesota catlinite is buttery smooth and can be cut with a regular hacksaw or even a knife, it comes out of the ground a pinkish color often with a cream layer protecting it from the hard quartzite. It is weaker and more subject to breaking under stress than Utah pipestone. Most catlinite deposits exist beneath the level of groundwater or are in deep enough layers where the soil is constantly moist as the iron compounds which give catlinite its red color quickly convert into iron oxides when exposed to the elements and the stone degrades and breaks down.

The red catlinite from the Pipestone, Minnesota quarries is a soft claystone bed which occurs between layers of hard Sioux Quartzite. Only hand tools are used to reach the catlinite so it takes a long time to get to it. Only enrolled Native Americans are allowed to quarry for the stone at the Pipestone National Monument, and thus it is protected from over-mining. Another quarry is located near Hayward, Wisconsin on the reservation, which the Ojibwa have used for centuries. The stone there is harder than the stone from Pipestone National Monument.

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