Fluorrichterite is a rare mineral, known from only
one location. It is found near Wilberforce, Ontario
in a skarn formation. The skarn is a term for a rock
that is the product of a chemically unusual magma body
that has intruded into and recrystallized a "dirty"
limestone. The "dirty" limestone is not composed
of just calcite, CaCO3, like "clean" limestone
but is mixed with silicates and/or phosphates, etc.
This mixing of the hot chemically unusual liquids and
volatiles of the magma with the different minerals of
the "dirty" limestones produces some interesting
and rare minerals after all the recrystallizing is done.
One of these is of course, fluorrichterite.
Fluorrichterite forms well shaped crystals that can
have a pearly luster. Its luster is higher than most
members of the amphibole group possibly because of the
unusual presence of fluorine which comes from the unusual
magma chemistry. Mixed with fluorrichterite in the white
recrystallized calcite of the skarn are well formed
crystals of biotite making specimens extra special.
Fluorrichterite is a brand new mineral, only receiving
official recognition in 1996, although it has been collected
for many years by many collectors. During this time
specimens have been called various names in addition
to fluorrichterite such as fluor-silicic-edenite, richterite
(another amphibole mineral), augite (a pyroxene!) and
many others. Its good to get this straightened out finally.