24 EDWIN C. ECKEL 



present exposed in the quarry of the Eureka Slate Co. With 

 the exception of the usual decomposed material near the ground 

 surface, the green slate dike furnishes merchantable slate from 

 the outcrop down to the tunnel level. 



The green slate splits readily, though not with as smooth a 

 surface as the black slate ; and gives a pleasant color contrast 

 when used for trimming or lettering on black slate roofs. It 

 bears punching and countersinking very well, and is sufficiently 

 strong for roofing use. 



Compared with the large amount of merchantable black slate 

 now in sight, the total quantity of green slate is so small that no 

 attempt is being made to push its sale for use separately from 

 the black slate. It is now supplied solely as an ornamental trim- 

 ming for black slate roofs, for lettering, and similar uses, 



Edwin C. Eckel. 

 U. S. Geological Survey. 

 Washington, D. C. 



