Geology and Mineralogy of a part of Massachusetts, §c. 11 
nite in our country, the feldspar is whitish. At least in this 
section, this aggregate has always a whitish aspect, from 
the white or yellowish white colour of the feldspar 
_As we descend from the eastern range of hills, into the 
vallies of the Housatonick and Hoosick rivers, we leave the 
hornblende entirely. None of it is found in the mica-slate 
of the middle and western parts of Berkshire Co. Only 
small fragments of the hornblende aggregates are washed 
down, by the streams into the eastern part of these vallies, 
Besides these hornblende rocks, there is another rock, as- 
sociated with them, whichis composed of hornblende, quartz 
and mica, or of hornblende and mica-slate. This aggre- 
gate has often appeared more abundant than either of the 
hornblende aggregates already mentioned. Occasionally 
the quartz nearly or quite disappears, and the mixture is 
hornblende and mica. In Sandisfield, Tyringham, Mid- 
dlefield, &c. this aggregate may be found. It passes into 
primitive greenstone slate, and differs so little from it in 
its general appearance that a specific name may not be ne- 
cessary. 
On the rocks of hornblende is generally found the fine 
epidote of Middlefield, Chester, and Worthington. In fis- 
sures in mica-slate, and on hornblende in Chester, is 
found stilbite, chabasie, crystals of carb. of lime, &c. 
he mica-slate contains numerous beds of 
Serpentine. 
Serpentine is ranked with the rocks by Jameson, Bake- 
well, MacCulloch, &c. It is scattered, like the primitive 
ornblende rocks, widely on the eastern part of the sec- 
tion. It is primitive serpentine, and very different from 
that which occurs in the lower series of rocks, having that 
sub-crystalline appearance so peculiar to primitive rocks. 
It is found in large beds in Middlefield, Russell, just with- 
out the map at the south-east of Middlefield, and Windsor. 
I mention these three towns, because they extend over 
that breadth of country, along which both to the south and 
far north into Vermont, the serpentine is found in exten- 
om beds. See the subjoined catalogue of simple mine- 
rals. 
