MAGNETITE AND PYRITE. 



131 



ANALYSES OF MAGNETITES. 



(Caution in interpreting analyses is again emphasized asunder 2.01.26.) 



PYRITE. 



2.03.16. Example 16. Pyrite Beds. Beds (veins) of pyrite, 

 often of lenticular shape and of character frequently analogous to 

 magnetite deposits, in slates and schists of the Cambro-Silurian or 

 Huronian systems, and less often in gneiss of the Archaean. Slates 

 are most common, and gneiss least so. They extend from Canada 

 down the Appalachians to Alabama, being found at Capelton, 

 Quebec ; Milan, N. H. ; Vershire, Vt. ; Charlemont, Mass. (An- 

 thony's Nose, N. Y., and the Gap mine, Pennsylvania, being pyr- 

 rhotite, will be mentioned under " Nickel " with other similar oc- 

 currences) ; Louisa County, Virginia ; Ducktown, Tenn. (see above, 

 Fig. 6), and at many points less well known in Alabama. Also 

 at Sudbury, north of Lake Superior, recent developments have 

 shown an enormous deposit, specially discussed under " Nickel." 



2.03.17. The ore bodies lie interbedded in the slates, and often 

 the different lenses overlap and succeed each other in the footwall 

 and exhibit all the phenomena cited under magnetites. Chalco- 

 pyrite is usually present in small amount, and where the copper 

 reaches 3 to 5% they are valuable as copper ores. (See under 



ton Mines." etc., M. E., XVII., p. 616. I. Olmsted, " The Distribution of 

 Phosphorus in the Hudson River Carbonates," M. E., Colorado meeting, 

 June, 1889. W. B. Potter, Analyses of Missouri ore published in Mineral 

 Resources, 1890, p. 47. 



