pyrrhotite
... that troilite, a form of pyrrhotite, is extremely rare on Earth but is abundant on Mars ?
... that troilite, a form of <b id="mwBqQ"><a href="./Pyrrhotite" id="mwBqU" rel="mw:WikiLink" title="Pyrrhotite">pyrrhotite</a></b>, is extremely rare on <a href="./Earth" id="mwBqY" rel="mw:WikiLink" title="Earth">Earth</a> but is abundant on <a href="./Mars" id="mwBqc" rel="mw:WikiLink" title="Mars">Mars</a> <i id="mwBqg">(pictured)</i>?