Pipestone, also called catlinite, is a red clay formed from metamorphosed mudstone. It can appear in a range of colors, from salmon pink to deep red. The color is determined by the concentration of iron oxide in the sample. Most blocks have small white impurities called "stars."Know More
As of 2014, pipestone is a relatively rare metamorphic rock type. In North America, it is most abundant in southwestern Minnesota, where native people have quarried it to make ceremonial objects for 3,000 years. The rock's name derives from its common use in carved pipes that are used in the religious ceremonies of local tribes.