THE MINERAL COLLECTOR. 



33i 



eral. They have a bright brassy-yel- 

 low color, and a very brilliant lustre, 

 which makes them exceedingly attrac- 

 tive. 



Pyrite is a very widely distributed min- 

 eral. Few ores, of whatever kind they 

 may be, are entirely free from it. It 

 is often present in sufficient qviantity 

 to serve as the basis of extensive min- 

 ing operations. Though on iron com- 

 pound, it is not suited to use as an 

 iron ore, for the sulphur in it amounts 

 to 53.4 per cent., while the iron con- 

 stitutes only 46.6 per cent. Notwith- 



mines at Franklin Furnace, N. J., in 

 the northwestern corner of that state. It 

 has the usual bright brass-yellow color 

 and brilliant lustre. Its faces are deeply 

 striated in places, showing a tendency 

 to form cube faces ; other forms are 

 also present on the crystal. 



The white limestone which contains 

 the pyrite was probably at one time 

 a simple sedimentary rock, a consoli- 

 dated lime-mud. Together with other 

 elements, this new rock contained iron. 

 When the great Appalachian mountain 

 system was in process of formation, 



IV. HALITE FROM BORAX LAKE, SAN BERNARDINO COUNTY, CALIFORNIA. 



standing this, its sulphur content is 

 valuable. It is of increasing impor- 

 tance as a source of sulphuric acid 

 fumes for the manufacture of vitrol. 



Pyrite is classed in the isometric 

 system, in regard to its method of 

 crystal formation, its principal forms 

 being the cube and the octahedron. 

 The cube is well shown in the Colo- 

 rado specimen, and the octahedron in 

 the one from Franklin, N. J., else- 

 where described. Wonderfully perfect 

 octahedrons were also obtained from 

 the old French Creek mines in Penn- 

 sylvania. 



III. Pyrite, Franklin, N. J. 



The large octahedron of pyrite here 

 shown came from the famous zinc 



this limestone was crushed and meta- 

 morphosed in the mountain building; 

 the limestone, pure calcium carbonate, 

 crystallized, and the impurities in it 

 separated from it, forming new com- 

 pounds, which crystallized in their 

 turn. Thus the pyrite crystals were 

 formed, as the familiar garnets were 

 formed in the metamorphic schists of 

 many regions. 



The pyrite is not a common thing in 

 the limestone at Franklin, and lately it 

 has been becoming scarcer and scarcer. 

 This crystal is an exceptionally large 

 one. The crystals from Franklin sel- 

 dom show simple forms ; there are 

 many complicated and interesting ones 

 that have been found from time to 

 time. 



