OF PYRITES AND GYPSUM.
315
—forms which are referable to what is now generally known as
the orthorhombic system. Hence two distinct species have to be
recognised. In 1845, Haidinger, a distinguished mineralogist in
Vienna, suggested that the orthorhombic species should be
called Marcasite, whilst the term Pyrites or Pyrite was reserved
for the more common cubic species. This terminology is now
generally adopted by mineralogists.
Unfortunately, however, there has been much confusion in
the use of the terms, for some of the older writers employed the
words in a sense quite different from our present usages, so that
their marcasite is our pyrites !
For example, in the eighteenth century it was fashionable to
wear what jewellers called "marcasites," but these stones were
really cubic pyrites, "rose-cut" and polished. Visitors to
Ireland at the present day purchase shamrock brooches, and
other trivial objects cut in pieces, of black shale, having the
surface studded with brilliant little crystals of cubic pyrites.
Curious superstitions associated with pyrites led to its being
regarded as a stone related to the state of its wearer's health, and
hence it was known in Germany as the Gesundheitstein or
"Health stone." When the wearer became sick the marcasite
tarnished. The curious word marcasite is said to be of Arabic
origin, having perhaps reached us by way of Spain. Some of
the older writers had an easy way of settling its meaning : thus
Borlase derives it from the verb mar care, to stamp—"a name,"
he says, "proper enough for any fossil, which, for aught we know
at present, has only the appearance, mark or outward testimonies
of metal," Those who are curious about the meaning and origin
of the word marcasite will find a learned paper by Dr. Sadebeck
in the Nettes Jahrbach fur Mineralogie for 1878, p. 289.
It is sometimes found convenient to extend the use of the
word "Pyrites" so as to include both forms of iron-disulphide,
the cubic species being then distinguished as Pyrite. Professor
Alexis Julien, who has written much about these minerals, uses
the term pyrites in a yet more comprehensive sense, so as t6
embrace not only Pyrite and Marcasite but also a third species
of iron sulphide known as Pyrrhotite or Magnetic Pyrites. In like
manner the "Century Dictionary," defining "Pyrites," says:
"It is commonly called Iron Pyrites, which term, however, also
includes the related orthorhombic species marcasite as well as
magnetic pyrites, or pyrrhotine."