302 IRVING. 



cupy only the depressions of the Algonkian surface, so that the 

 ore frequently comes into direct contact with the slates. The 

 roof is sometimes shales, and at others porphyry, and the entire 

 mine, like many of the others examined, is seamed with dikes. 



The Clinton. — Of the mines on the upper contact the Clinton 

 was the only one carefully examined. The shoots extend in a 

 northwest and southeast direction, and the usual verticals ap- 

 pear. The ore is in a bed of lime shales, and rests on a 

 quartzite floor consisting of one of the more massive members 

 of the upper strata of the Cambrian. The shoots are thin and 

 of less lateral extent than are those on the lower quartzite, but 

 in other respects they show no essential difference. The hill on 

 which the mine is situated contains many sills of porphyry with 

 Cambrian partings between. Much of the ore is of lower grade 

 than the ores on the lower contact, and it is said to carry a higher 

 relative percentage of silver. 



Although the very first siliceous deposits to be opened up in 

 the hills, the mines of Green Mountain have not been in opera- 

 tion for some time, owing to litigation. The ores, however, 

 carry quite high values in gold and silver. They contain con- 

 siderable galena and some copper, which frequently manifests 

 itself in green coatings. 



3. Croii'ii Hill District. 



In the Crown Hill district very little work has yet been done, 

 there being but one producing mine, that of the "Two Johns." 

 The district is, however, a promising one, and owes its tardy 

 development rather to ill-advised mining, and to its position 

 at the very top of the Cambrian series (thus necessitating a 

 considerable depth of shaft to reach the lower quartzite) than to 

 any absence of ore deposition. In'the Two Johns the ore lies 

 on the lower quartzite. 



4. Shccptail Gulch District. 



The ore is found in shoots on the basal Cambrian quartzite, 

 as it dips away from the Algonkian toward the northeast. This 



