20 Geology and Mineralogy of apart of Massachusetts, §e. 
The argillite along the east side of the Taconick range, 
has sometimes a little talc mixed with it, forming talco-ar- — 
gillaceous slate. 
Beds of argillite, resting on limestone, are found low 
down ip the valley of Williamstown. 
The primitive _argillite is not disintegrated so rapidly as 
the transition. The soil of the argillaceous district is more 
fertile and productive than of any other portion of the section, 
except the alluvial. This fact has been remarkec pr ne 
riculturalists, and corresponds with the statement of so 
English geolozists. The same fact i is noticed in the Géolows 
of Rensselaer County, page 23. 
On the use of roof slate upon buildings, it may be prop- 
er to mention a fact sta y respectable gentleman 
af Troy, tat the sm 
es of slate found to 
an the larger, former e- 
ing much less liable to coal val loosen by the action of 
heat and cold than the latter. 
The argillite seems to pass into chlorite slate occasional- 
ly,or, at least, chlorite slate i “¢ associated with it, and talco-mi- 
caceous slate, i in several places. Chlorite slate occurs in 
Pownal, Petersburg, &c. On the east side of the Taconick 
range, it often contains magnetic oxide of iron, in octoedral 
crystals. In Petersburg it forms considerable hills, and is 
found in considerable quantities in the towns south of’ this 
lace 
re the south of Bennington, Vt. is a small hill of ae 
which approaches the variety, called graphic slate. Its ¢ 
lour is dirty black, fracture rather earthy, and streak ome 
ack. It contains erystals of sulphuret of ivon, which are 
often changing to the hepatic sulphuret. The soil arising 
from the disintegration of the slate, is nearly black. The 
whole hill has the appearance, which might result from a 
recent combustion. Several years since a shaft was sunk 
here for the purpose of finding coal. It was not indeed 
continued through the rock. The geologist is aware that 
coal is not to be expected at this place, such is the geologi- 
cal position of the rock. The principal road from Ben- 
nington to Pownal passes over the side of this hill of argil- 
lite. The slate here is also tortuous, noticed by Prof. Sil- 
liman, Vol. IV, p. 43. 
