This is the mineral Magnetite. It has a metallic luster and a black streak that is best seen when drawn across a white ceramic streak plate. It’s positioned about mid-range on Mohs hardness scale, ranking between 5.5 and 6.5. The mineral has a specific gravity of 5.2 and thus feels relatively heavy in your hand. Magnetite has no cleavage. Its chemical formula is Fe3O4, making it part of the Oxide chemical family. Oxides are defined by the presence of Oxygen chemically bound to one or more metals. Magnetite is a very common metallic mineral in igneous and metamorphic rock. It’s also prevalent in sedimentary rock beds that formed during Earth’s Paleo-Proterozoic Geologic Era, which occurred between 2.5 and 1.6 billion years ago. These Pre-Cambrian rocks display distinctive bands of deep red, Iron rich layers interspersed with lighter colored Chert layers that are iron deficient. Chert is a form of the mineral Quartz that has crystals too small to be seen without the aid of a microscope. Sedimentary rocks with these characteristics are called Banded Iron Formations, or BIFs, and can be several hundred meters thick. They are common around the world and have been identified on every continent except Antarctica. In North America, Banded Iron Formations, and thus the mineral Magnetite, are concentrated in the Iron Range. Note that some Banded Iron Formations contain the mineral Hematite, which is another Iron-rich mineral. North America’s Iron Range constitutes dozens of Iron ore mining districts around Lake Superior, in both the United States and Canada. Given its Iron content, coupled with the fact that our modern society is highly dependent upon Iron and Steel, it’s perhaps not surprising that Magnetite is a vital resource for human civilization. Another distinguishing characteristic of this mineral, especially apparent in its massive form, is the fact that it’s magnetic. This property is due to the electron configurations within the mineral. Samples are easily identified simply by using a magnet and testing for an attractive force. Such specimens are also known as Lodestone and were used for centuries to magnetize compass needles.