LA.EAMIE HILLS. 17 



however, is black, and unctuous to the touch : it contains but little iron- 

 pyrites. Deposits of sufficient size to be worked are said to occur, if the 

 mineral were only of the requisite purity. The following analysis is by 

 Mr. E. W. Woodward: 



Graphite • '. - 51.35 



Alumina 11.50 



Ferrous oxide 1.71 



Manganous oxide 0.24 



Lime 1.44 



Magnesia 3.21 



Sulpkir 1.00 



Silica 24.59 



Water 4.38 



99.51 

 Oxygen eq. to Fe Ss 0.27 



99.24 



Besides the larger rock masses already mentioned, the hills are char- 

 acterized by the presence of certain mineralogical features, and accidental 

 minerals, which are developed more or less throughout their entire length, 

 and are of importance in comparing the relations of the Laramie Hills with 

 other well-dej&ned Archsean ranges. Narrow veins of white vitreous or 

 milky quartz are common, penetrating the granites, rarely more than a 

 few inches in width, with a strike almost always a few degrees west of 

 north, although there are some exceptions to this rule. Usually the quartz 

 is quite pure, with the exception of small amounts of ferruginous min- 

 erals. Small quantities of compact yellowish-green epidote accompany 

 the quartz, usually occurring on the side of veins or seams; it is never 

 very abundant. It occurs on South Crow Creek, near where the road 

 from Sherman crosses the canon, and again on the plateau summit 

 west of Lron Mountain. Magnetite and ilmenite also accompany the 

 quartz veins in small, granular fragments,. and may be traced for consid 



2 D G 



