ELIZABETHTOWN AND PORT HENRY QUADRANGLES 1 39 



The ore occurs in a moderately large mass of gabbro which can 

 be traced in the vicinity. It is a dark green or black rock, con- 

 sisting of augite, hypersthene, brown hornblende, garnet, original 

 basic plagioclase, charged with pyroxenic dust and minute spinels, 

 secondary plagioclase in clear rims around the last named, and of 

 the magnetite-ilmenite mixture. The ore is lo feet or more thick, 

 and forms a flattened body, which strikes into the hill n. 70° -80° e. 

 and dips 50° south. An open cut has been excavated 30-40 

 feet deep and 25 feet high. From its mouth the old dump of 

 broken ore streams like a talus down to the lake shore. To the 

 south another small opening is reported but this has not been vis- 

 ited by the writer. 



A\'hile the rock mass is faintly foHated from dynamic effects, 

 there is no sharp transition from ore to rock. The former is 

 simply a basic phase of the latter and the exposures are so good 

 that this locality is a specially favorable one for the study of the 

 relations. 



In cracks through the ore a curious isotropic green substance is 

 somewhat rarely found which contains some dusty magnetite and 

 the decomposed remains of feldspar crystals. It has been pre- 

 viously described by the writer as a glass, but its identity can not 

 be sharply determined without a quantitative chemical analysis. 

 Its specific gravity is 2.822 which is higher than the common iso- 

 tropic minerals which might occur in these relations. 



An analysis of the wall rock has been made by W. F. Hillebrand 

 and also one of the ore, nos. i and 2 below. No. 3 is an analysis 

 by George W. Maynard, made in the early seventies. Nos. i and 

 2 are from the 19th Annual Report of the United States Geological 

 Survey, volume 3, page 402 ; no. 3, Journal of the British Iron 

 and Steel Institute, volume i, 1874. 



I 2 3 



SiOo 47 . 88 17-90 16 . 46 



TiOv 1.20 15-66 1470 



Cr.Oa tr; ? .51 



AI2O3 18 . 90 10 . 23 .34 



FeoOa 1.39 15-85 3843 



FeO 10.45 27.94 23.40 



NiO.CoO -02 not det. not det. 



MnO .16 tr. .23 



MgO 7.10 604 2 13 



CaO 8.36 2.86 3.54 



SrO tr 



BaO tr. 



