Located in rural southwestern Minnesota, the pipestone quarries are considered a sacred site by many American Indians. For the last 3000 years, tribes across the central region of North America have traveled to this site to quarry. Today, they still travel long distances to this site to continue the tradition of pipestone quarrying and pipemaking. Since 1946, the 56 pipestone quarries have been managed by issuance of a quarry permit. More information on obtaining quarrying permits.
The quarrying of pipestone is often an underappreciated part of the tradition surrounding pipemaking. The task of extracting pipestone from the earth is a slow and labor intensive process and the hand tools used today are not much more advanced than the tools and methods used in centuries past. The process can require many days of physical labor with only the use of hand tools such as sledgehammers, pry bars, chisels, wedges, and steel bars allowed. For someone not already in good physical condition the process is slowed or should not be attempted at all.
Depending upon the specific quarry, experience has shown that quarrying time can be estimated at two to six weeks. The layer of pipestone is sandwiched between layers of very hard Sioux Quartzite rock. Depending upon a quarry’s location on the quarry line the upper layer of quartzite can be four to ten feet thick above the pipestone layer. Prairie plants and soil varying in depth from one to six feet cover the upper layer of quartzite.
By use of shovels and wheelbarrows the soil layer is dug up and moved to the rubble piles at the rear of the quarries. All subsequent quartzite pieces are also moved to the rubble pile.
The upper layer of quartzite is itself composed of multiple layers of quartzite, with vertical fractures and cracks in the rock. Wedges or chisels are placed into these cracks and then driven down with sledge hammers to break loose individual blocks of quartzite. Upon loosening a piece, it is worked free with a steel pry bar and allowed to drop to the floor of the quarry. Heavy sledge hammers are then used to break the bigger chunks of quartzite into smaller manageable pieces that can be lifted and thrown out the back of the quarry. The process of breaking out the quartzite is repeated many times until the pipestone layer is exposed.
The smaller pieces are also used in building a rock retaining wall along the front of the rubble pile. The rock wall serves as a “fence” of rock so that as additional quartzite and soil are thrown or stacked at the rear of the quarry the fence will prevent the rubble pile from collapsing back into the quarry. Building a retaining wall is an essential part of managing a quarry and a very important safe-guard for quarriers.
Once the pipestone is exposed, care must be taken in removing the stone as it is very fragile and when handling large slabs it can break. The pipestone layer may vary from 10 to 18 inches thick and it too is composed of multiple layers from 1 ½ to 3 inches thick. Individual layers are carefully removed one slab at a time by driving wedges into the natural horizontal seams. The natural vertical cracks in the quartzite carry down through the pipestone which allows the quarrier to remove the pipestone layers in irregularly-shaped slabs. More on Geology.
The quarries are located in the bottom of a bowl-shaped drainage. In the spring and early summer months groundwater from rain and snow melt collects in this low laying area, filling the quarries with water. Most quarriers prefer to work during the summer to late fall months to avoid the groundwater problems. Monument staff will assist quarriers by pumping water out of the quarries, but only upon 2 days advance notice of when quarrying is planned. Often, when it is high, groundwater will flow back into the quarries as fast as it is pumped out. Since continued pumping will not reduce the water level, it will not be attempted during these high groundwater periods.