WITH MARCASITE (PYRITE)
Specimens of quartz sold as with Marcasite inclusions from Brazil have
been analized and are actually resuted to be of Pyrite. Usually these "Pyrites"
are characterized by a flatted morphology filling fractures of the quartz
crystals. They are formed by secondary pyrite generation. The "real" Pyrite
inclusion also from Brazil are usually three-dimensional primary cristals
included in quartz. The shape is usually round and occasionally can
be squared with a radial structure. Oxidation of the pyrite can results
in yellow to brown halos and a complete alteration of the pyrite sulfide
in Iron oxides.
The location of this deposit is described as Sao Joao de Safira, Minas
Gerais, that is an area very rich in famous tourmalinipherous pegmatites
as Pederneira and Cruzeiro Mines.