344 



Scientific Geology. 



In the mica slate in the southeast part of Conway, a vein of quartz, 

 six or eight feet thick, and nearly perpendicular to the horizon, runs 

 N. 20° East. It is the gangue of two ores, the red oxide of iron and 

 the gray oxide of manganese : which, however, do not occur in it 

 abundantly at the surface. But they have imparted a great variety of 

 colours to nearly the whole gangue; and rendered a part of it very 

 compact. Hence we find there brown and yellow jasper, and some- 

 times chalcedony. The various colours, black, white, red, yellow, 

 and brown, are often intermixed, sometimes irregularly, forming 

 breccia agates -; and rarely in parallel stripes, forming a banded agate. 

 Some of these, if polished, would form I doubt not elegant ornaments. 

 (Nos. 738 to 743.) 



At the same place we find a delicate variety of tabular quartz, in 

 which the lamina are as distinct and thin as the folia of feldspar. 

 Sometimes they are so arranged as to present the appearance of pseu- 

 domorphous crystals ; and sometimes they so intersect as to form 

 cells. In the cavities of the compact quartz, there sometimes occur mi- 

 nute crystals of quartz, giving the geodes a rich appearance. (Nos. 

 746, 747.) 



About one mile northeast of the College in Amherst, I have recent- 

 ly found numerous bowlders almost exactly resembling those in Con- 

 way just described. Chalcedony and hornstone, however, occur 

 here rather more commonly. I cannot doubt but these masses were 

 brought to that spot from the mica slate which occurs a few miles 

 north, both in Amherst and Leverett. The delicate greenish horn- 

 stone, found by Mr. Shepard in Amherst and Pelham, some years 

 since, undoubtedly had the same origin. I do not despair of discov- 

 ering the parent vein. 



Some of the quartz of these bowlders is yellow and in small crys- 

 tals. Yellow and irised quartz also occurs in mica slate in Fitchburg. 

 Jasper is found on the banks of Deerfield and Westfield rivers in rol- 

 led masses, and probably originated in mica slate. 



The gangue of the lead, zinc and copper ores in Hampshire coun- 

 ty, is chiefly crystalized and radiated quartz : and these veins some- 

 times occur in mica slate : but as they generally traverse granite, I 

 shall describe them in treating of that rock. 



Not having visited the beds of manganese and iron marked on the 

 map in Hinsdale and Winchester, New Hampshire, I am not sure 

 that they occur in mica slate, though strongly suspicious that such is 

 the fact. In the first part of this Report I have stated all the facts 



