August 1997

Dr. Ed Mathez and Margaret Carruthers meet a team of geologists from the University of Washington at the Stillwater Mine in Montana, which provides around 2% of the world's platinum. A 17 ton harzburgite boulder with a chromitite seam, the second largest sample in the exhibition, is collected along with a boulder of massive chromitite. They will help to show how elements important to humanity, such as aluminum, iron, salt, gold, etc. become concentrated in the Earth's crust. The scientists also collected boulders of anorthisite, gabbro, and norite. These samples tell the story of cooling and crystallization in large igneous intrusions. They form when magmas similar to those that erupt from volcanoes get trapped within the continental crust.

A stream runs along a hill near the Stillwater Mine in Montana

photo credit: Denis Finnin, © American Museum of Natural History