Pyrite is an iron sulfide mineral and one of the most ubiquitous minerals of earth's crust. It is found in igneous, metamorphic and sedimentary rocks and crystallizes at both high and low temperatures.
Large amounts of nickel are used in the specialty steel industry for stainless steel and related alloys. And also in nonferrous alloys (or mixed with metals other than steel) and super alloys (metal mixtures designed to withstand extremely high temperatures and/or pressures, or to have high electrical conductivity).