Jaspilite at Jasper Knob (Jasper Hill) in Ishpeming, Marquette County, Michigan, USA. The rock consists of alternating bands of jasper (red chert, which is cryptocrystalline quartz), red hematite and silvery-grey specular hematite. It is part of the Negaunee Iron Formation of the upper Menominee Group of the Marquette Range Supergroup of Paleoproterozoic age. The rock of this outcrop has an iron content of about 40%.