It is also one of the most common fossils in the Gunflint chert. This group contains both the Rove and Gunflint Iron formations. Ancient microfossils have been found in the banded iron formations of the Gunflint Chert. The Gunflint Chert is composed of biogenic stromatolites. Loon Lake is a lake in Cook County, Minnesota, off of the Gunflint Trail. The Gunflint microfauna can be split into two broad categories&colon; filaments and spheroids. The Gunflint then proceeds southeastward, with its terminus at Grand Marais, Minnesota on Lake Superior. The Gunflint Range is a mountain range in northeastern Minnesota, U.S., and western Ontario, Canada.