MINERAL RESOURCES OF THE STATE OF NEW YORK II7 



like the Sterling, Forest of Dean and Tilly Foster occurrences, are 

 in thin beds lo to 15 feet thick at most and consequently the eco- 

 nomic limit of exploitation was reached at shallow depths under the 

 conditions of mining that formerly obtained. In all there are prob- 

 ably over 50 of these smaller bodies that have been worked in the 

 past. The aggregate output of shipping ore has been approximately 

 6,000,000 tons. 



Sterling Lake. The output at Sterling Lake is now taken from a 

 single deposit, known as the Lake, one of the numerous bodies that 

 occur in the vicinity and that together have supported a mining 

 industry for the last 150 years and more. The different deposits 

 vary greatly in their physical features as related to form and content, 

 although situated in the same general geological surroundings, so 

 far as cursory examination shows. Some are thin sheets lying fiat, 

 or slightly inclined, others are attenuated lenses with a moderate 

 to steep dip and usually with a pitch to the north, and still others 

 are developed as narrow, elongated shoots with the long axis on the 

 pitch which likewise is to the north. More complex forms result 

 from differential compression and folding of these simpler types. 



The principal deposits lie within a belt that begins near the New 

 Jersey line and extends some 5 or 6 miles to and beyond Sterling 

 Lake. It is a part of a much larger ore zone that reaches into New 

 Jersey on the south and extends in a general northeasterly direction 

 across Orange county to the Hudson river. Beginning at the south, 

 within a short distance of the state line, the series include the Steel 

 mine which outcrops on a ridge at about 800 feet A. T. and is based 

 on a band of ore striking N. 20° E. It is opened by a few pits on 

 the south end. The same band of ore extends north beyond the 

 hill under the adjoining valley. The next deposit is the Crawford, 

 located on a lens which begins near the base of the succeeding ridge 

 and pitches northward under it; it is opened as a pit and under- 

 ground drift for a distance of 500 feet on the strike. It measures 

 20 to 40 feet in width from wall to wall, but includes bands of lean 

 or barren gneiss intercalated with the magnetite. An interesting 

 feature of its geology is the fact that the ores cut obliquely across 

 the bedding of the gneiss. The presence of massive granite on the 

 eastern or hanging side (the dip is about 75° E.) may be noted, 

 whereas the foot wall consists of the usual hornblende gneiss. The 

 granite on the north end also caps the ore body. Another lens lies 

 a little west of the Crawford and is open in the Brennan pit. It 

 trends northwest. 



The California mines are about 7000 feet farther north, on the 

 opposite side of the ridge on which the Sterling and Lake deposits 



