88 
IKON PYRITES. 
Iron Pyrites, &c. 
Before commencing with the ores from which iron is made, a case of 
minerals has to be noticed, which, although containing a large per¬ 
centage of iron, are not employed for the production of that metal. 
Among these the following are the more important: 
Iron Pyrites, Pyrite, Mundic, Brasses, Sulphur, under which 
various names it is locally knovm, is bisulphide of iron, containing in 
100 parts :— 
Iron - - - 45‘77 I Sulphur - - - 54*23 
It is one of the minerals most largely diffused throughout the earth, 
and it is noticeable that this compound of sulphur and iron is di-morphous, 
one species being that commonly known under the above name, of a brassy 
yellow colour, and crystallizing in the cube and its derived forms ; the 
other being— 
Marcasite, white, spear, or cocks-comh Pyrites, crystallizing in veiy 
different forms belonging to the Rhombic system of crystals, and 
generally of a paler colour than the former. For the production of 
sulphur or of sulphuric acid (oil of vitriol), these substances are largely 
employed, and besides lieing imjiorted from Spain, Portugal, and Belgium, 
are so abundantly yielded by our own metalliferous mines, where they 
accompany copper ores, and sometimes form of themselves large veins, that 
about 100,000 tons of Pyrites are annually raised, partly by our Western 
mines, but chiefly in the county Wicklow. 
Magnetic Pyrites, Pyrrhotine, a comparatively rare substance, of a 
more bronzy colour than the above, contains :— 
Iron - - - 60*5 j Suljfliur - - 39*5 
It is easily distinguishable from the others by attracting the magnetic 
needle, and is noticeable as frequently yielding a small proportion of 
cobalt or nickel. 
The following species are represented, but are not minerals employed 
for any economic purpose :— 
ViviANiTE, blue iron {phosphate of ironf 
CiiiLDRENiTE {pliospliate of iron and alumina'). 
PriARMACOSiDERiTE, Cubc-ore {arseniate of iron). 
Wall-case 46. i 
Shelf I. I 
193. Iron Pyrites, {bisulphide 
of iro7i,) cubically crystallized, 
and massive. 
Nangiles Mine, Gwennap, Redruth 
district, Cornwall. 
From the Exhibition of 1851. 
194. Iron Pyrites, crystallized 
in large cubes. 
Cornwall. 
195. Iron Pyrites, the penta¬ 
gonal dodecahedron, partly im¬ 
bedded. 
Cornwall. 
Presented by G. B. Greenongh, E.R.S. 
196. Iron Pyrites, cubical, 
but irregularly crystallized. 
From Strontian, Argyleshire, Scot¬ 
land. 
Presented by Sir J, M. Riddell, Bart. 
1851. 
197. Iron Pyrites, crystallized 
in cubes modified by planes of 
pentagonal dodecahedron. 
Mount Mine, Cornwall. 
198. Iron Pyrites, in casts 
after crystals of Barytes. 
Huel Mary Ann, Cornwall. 
199. Crvstallized mass of Iron 
%/ 
Pyrites, on nucleus of Copper 
Pyrites and Quartz crystals. 
Cornwall. 
