History and Geology of the Minnesota Pipestone Deposit


THE HISTORY
Artist George Catlin is generally recognized as the first white man to see the quarry and the beautiful, blood-red pipestone from the famous southwestern Minnesota deposit is named Catlinite after him. According to his journal, Catlin visited the quarry in 1835. Tall tales were common during the early explorations of the western regions and one narrative quoted Catlin as portraying how dangerous it was for a white man to attempt to visit the quarry - a sacred place to all Tribes. As that particular writer told it, Catlin claimed that in order to visit the quarry, he had to sneak to the site of the quarry for a quick visit under threat of death.
Whether or not that was really the case, we may never know for certain. But in a letter Catlin wrote about his visit to the quarry, he describes the site in enough detail that we know he was there.
To read the letter, click on this button.



carved pipestone
An early photo of a quarrying operation.

As a matter of fact and contrary to popular belief, Catlin was probably not the first white man to see the quarry nor was it apparently as dangerous an undertaking as his journal would indicate. About the first of September, 1832 Philander Prescott, a trader for the American Fur Company, was ordered to proceed to the Big Sioux River country located in what is now the State of South Dakota to hunt beaver. The Big Sioux, a tributary of the Missouri River, is about 20 miles west of the pipestone deposit and quarry. Prescott (for whom the town of Prescott, Wisconsin is named) describes the preparations of his Fur Brigade for its trip to the new trapping grounds;
"We got all things ready, loaded our carts, 8 in number. I had one cart for myself and family, and we went off all in good spirits..."
"There were about one hundred Indians - men, women and children. The first day we got on very well and the 2nd day went to the crossing of the Minnesota River and found the River fordable, and next day got all over and reloaded, ready for a start in the morning. We had two Frenchmen, hunters, and I got an Indian to go as guide and hunter both, and one of his brothers and a cousin of his went along."
After a number of days on the trail with his Brigade and family in tow, Prescott writes:
"The next morning we moved off in search of water, for where we camped water was scarce and the horses could not get enough. About noon we arrived at the famous place called the Pipestone quarry."
The Brigade spent a full day working the quarry but only managed to get enough stone for about 20 pipes. He described the deposit of Pipestone as follows:
"When I was there diggings were about 100 yards long, and at the south end the diggings are about ten feet deep. The pipestone is about a foot thick, but in seams from 1/4 to 3 inches thick; in the deep part of the quarry there is more clay and the pipestone is speckled. Otherwise it has pale, white spots, and some has deeper red spots. And some is a pure red and smooth as marble, and fire does not crack it."
A note at the end of the section of Prescott's journal covering the period from 1829-1833 states that "Though [the quarry] is not shown on any map earlier than 1703, records indicate that as early as 1637 Indians living far from the quarry treasured the pipes made from the stone found there."

THE GEOLOGY
In a nutshell, the Early Proterozoic Sioux Quartzite of southwestern Minnesota accumulated as sedimentary sand layers deposited by streams that flowed across an erosional surface developed on older Archean rocks. These deposits were metamorphosed by heat and pressure to produce the metamorphic layers of quartzite seen today. The thin 2 to 6 inch layers of reddish-brown catlinite - a metamorphic claystone argillite - is normally found sandwiched between layers of quartzite which is often found under an overburden of 10-15 feet. The catlinite deposits of southwestern Minnesota are estimated to be between 1.6 billion and 1.8 billion years old.
For more information about geologic time, visit our Geologic Time Page.

The specimen above is a great example, on a small scale, of how the deposits appear.

Catlinite is a mineral made up of diaspore, pyrophyllite, muscovite and hematite, along with traces of anatase and chlorite. Catlinite gets it rusty, reddish color from oxidized hematite - an ore of iron. It is composed of: silica (49.01 percent), alumina (35.17 percent), magnesium (0.23 percent), water (5.87 percent), potash (5.62 percent), ferric acid (3.06 percent) and titanium dioxide (0.44 percent).
Catlinite is very soft measuring 2.5 on Mohs Scale of Hardness. That is about the same hardness as a human fingernail and provides the unique sofness necessary for shaping it into pipes and other objects. For more about Mohs scale, go to our Mohs Scale page.