50 NEW YORK STATE MUSEUM 



derived from a feldspathic sandstone or arkose. The hornblende 

 gneiss and mica schist on the other hand, are doubtless to be 

 referred to an argillaceous deposit, and the crystalline limestone to 

 a calcareous one. The order of succession presented by the series is 

 thus a normal one, such as is found in sedimentary strata which 

 have been deposited on a gradually sinking shore line. 



Description of the mines 



Hammondville mines. The accompanying plan, reproduced 

 from the original recently prepared by the Oliver Iron Mining 

 Co., indicates the distribution of the principal deposits and to 

 some extent their underground continuations. The mine maps 

 of the Crown Point Iron Co. have unfortunately been destroyed 

 and complete details regarding the workings can no longer be had. 

 The present plan has been compiled from such records as are still 

 available and from the results of diamond drilling; it can be relied 

 upon no doubt as reproducing the more important features [fig. 3]. 



The deposits in all cases are surrounded by the plagioclase gneiss 

 which has been called the ore-bearing formation. They show no 

 relation to the latter in the way of gradation, but have well defined 

 boundaries. The only noticeable change in the gneiss "as the ore 

 bodies are approached consists in an increased proportion of mag- 

 netite, which gives it a somewhat darker appearance, and the 

 development at times of a hematite stain resulting from the oxida- 

 tion of this mineral. The magnetite seldom amounts to more than 

 5 per cent of the whole. 



In their arrangement and form the deposits are characterized by 

 great irregularity. Over 30 different openings have been made on 

 as many ore bodies. Whether or not they occupy a definite hori- 

 zon in the gneiss scarcely admits of determination, because the 

 foliation of the latter is so obscure that little can be learned as to 

 the stratigraphic structure. Putnam has expressed the view that 

 they do occur in such a relation. With due allowance, however, 

 for folding and faulting, the existence of which has been estab- 

 lished in the ore bodies themselves, it would be difficult to bring 

 them all into alinement, and it is more likely that there were 

 originally two or three parallel series of deposits, probably tabular 

 in shape; by compression and displacement these have been folded 

 and broken up into the large number of lenses, shoots, pockets and 

 bands now distributed with little apparent order. The strike per- 

 haps in the majority of cases is northeasterly, but it is sometimes 

 nearly east and west and occasionally northwest. The dip is more 



