Chamosite after Almandine

Unknown Owner

A superb example for this classic pseudomorph specimen showing a crystal of almandine just over 3.0 cm in height and set perfectly up on matrix. The almandine crystal is replaced by chamosite and in excellent condition. Collected in 2004.A pseudomorph is a mineral specimen in which one mineral replaces another while preserving the original crystals external shape. In the case of chamosite after almandine, the original almandine garnet crystal was chemically altered and replaced by chamosite, a chlorite group mineral. The resulting specimen keeps the typical garnet crystal form even though the internal composition has changed. Such specimens are valued because they clearly show the process of mineral replacement while preserving the earlier crystal shape.The Michigamme Mine in Marquette County, Michigan was part of the Marquette Iron Range in the Upper Peninsula, one of the earliest iron mining regions in the United States. Mining developed in the late 19th century to extract iron ore from Precambrian banded iron formation. Underground workings supplied hematite ore for the growing iron and steel industry around the Great Lakes. Like many mines in the district, production eventually declined as higher grade deposits were exhausted and mining shifted to other areas.