Q: What is pipestone and does it come only from Minnesota?
A: “Pipestone” is a much generalized term meaning exactly what it looks like, stone used to make smoking pipes. Throughout the millennia and among numerous cultures worldwide, many types of stone have been carved into pipes, probably at least as many as the kinds of things smoked in them. The requirements seem to be ease of working and some inherent esthetic appeal, often color.
Commonly carved materials include 1. soapstone (talc, steatite), 2. chlorite, 3. pyrophyllite, 4. specific clay minerals such as kaolin or sepiolite (meerschaum), and 5. argillite, deposits of very fine-grained mixtures of various minerals hardened to varying degrees by metamorphism, heat, and pressure. Argillites have many different colors and all can occur as massive deposits showing little or no bedding or layering so they carve uniformly in all directions. Material found in the Queen Charlotte Islands and carved by Haida tribal members is a well-known black argillite. Terminology can get a bit fuzzy here because we have geologists, archeologists, ceramicists, museum curators, art dealers, and stone dealers all using these same names but not always with the same meanings.
In North America “pipestone” is often taken to mean red material, previously (but erroneously) thought to come only from a small area in southwestern Minnesota. Red pipestone artifacts have been found at archeological sites throughout the continent and the material is still of unique importance in many Native American cultures. The Minnesota pipestone is also called catlinite. The entire catlinite deposit lies within the Pipestone National Monument and can be quarried only by Native American tribal members. It is not the only occurrence of red pipestone but properly it is the only catlinite.
Continental glaciers carried red argillite from other occurrences and deposited it throughout the upper Midwest and many of the original source locations have been found. Detailed scientific studies have shown that most red pipestones contain varying proportions of kaolin, pyrophyllite, diaspore, muscovite, and quartz. The red color is from hematite, iron oxide, which coats the mineral grains and fills the spaces between them. Some deposits, including catlinite, have their own unique proportions of these minerals — a chemical and mineralogical fingerprint. Catlinite, for example, contains pyrophyllite, diaspore, muscovite, and a little kaolin, but no quartz. With appropriate analysis it is possible to determine if a sample or artifact is catlinite from the Minnesota locality or red argillite from some other area.