Chemistry, morphology, modal mineralogy, and photomicrographs of amphiboles and other minerals in the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin, USA

The Ironwood Iron-Formation, part of the Gogebic Iron Range in Wisconsin, is a Paleoproterozoic Superior-type banded iron formation (BIF) with substantial iron resource potential. The development of a Mesoproterozoic contact metamorphic aureole related to the emplacement of the Mellen Intrusive Complex resulted in the production of a variety of silicate minerals in the western portion of the Ironwood Iron-Formation, including amphibole, pyroxene, and olivine. The presence of amphibole minerals, some of which occur in a fibrous habit, has complicated development of this resource due to potential human health impacts. This data release provides information related to amphibole and other minerals in order that commercial, regulatory, and other entities may obtain a better understanding of their impact on potential resource development.