43 ECONOMIC GEOLOGY. 



They have cut into pyritiferous schists, sinking upon a vein six feet 

 wide, richer than the usual mass of 40 feet thickness. Many bunches of 

 copper were taken out, and I understand from F. L. Bartlett, of Portland, 

 that nickel is present in the ore. 



On Gate's hill, in Berlin, is a vein showing the minerals pyrite, chalco- 

 pyrite, bornite, magnetite, hornblende, and tremolite. The ores are 

 sparsely disseminated. 



This region promises well to the explorer, and it will doubtless be 

 heard from in the future. Our map shows that the rocks continue here 

 from the Ammonoosuc district, though interrupted by intrusive por- 

 phyries. 



The Warren Mine. 



In the gneiss of Warren there is a bed of tremolite more than fifty 

 feet wide, in connection with which is a vein of copper and zinc. Mica 

 schist, dipping 45° N. 50° E., encloses the bed. Veins of pure copper ore 

 with reticulations of quartz abound in the hanging wall, and a bed of the 

 same material occurs along the line of the junction of the tremolite and 

 schist. Veins of the copper, bunches of iron pyrites, and a resplendent 

 black blende occur also in the midst of the tremolite, as well as a little 

 rutile. Most of the tremolite carries copper pyrites, and the rock must be 

 stamped and washed to allow of separation. The annexed plan shows 



'«*.;--'5' 



Fig. 7. — Plan of the Warren Mine. 



a, Qu.-irtz ; b, Ore vein; c, Trap. 



the mutual relations of the three trap dykes, veins of quartz, and the ore 

 It was prepared by Mr. Huntington, and is not drawn to a scale. 



vein. 



