OF PYRITES AND GYPSUM. 3I5, 



— 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 Mavcasite, whilst t!ie term Pyrites or Pyvite 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 niavcave, 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 Neiies Jahrhach fiir 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 Pi/rife. Professor 

 Alexis Julien, who has written much about these minerals, uses 

 the term pyrites in a yet more comprehensive sense, so as to 

 embrace not only Pyrite and Marcasite but also a third species 

 of iron sulphide known as Pyrvhotite 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." 



