Jeffersonite

Jeffersonite is a dark green pyroxene mineral, a manganese zinc enriched variety of augite, chemical formula, sometimes compared to aegirine. Jeffersonite is not a List of [minerals recognized by the International Mineralogical Association|recognized mineral name].
It occurs in pegmatites where it can form crystals up to long and in the contact metamorphic zone between limestone and various intrusive rocks. It is reported from the Sterling [Hill Mine], and from South Australia and Sweden.