18 Geology and Mineralogy of apart of Massachusetts, &c. 
ground. Even the ledges of the rock at this place, which 
appear firm, on being moderately struck, break off into 
masses which fall to sand. No peculiar reason for the dis- 
integration at this place is known to exist. The rock, be- 
fore disintegration, appears to be the same as that at other 
places, where no such process is going on. This sand is 
employed in sawing marble into slabs, and in the manufac- 
ture of glass. Itis said to have been transported to the glass 
factory in Utica, N. Y. It appears to be inexhaustible, and 
is excellent for the composition of crown and cylinder glass. 
In several places in this section, there is a quartzose 
Breccia, or rock of conglomerated quartz. It is always 
connected with the quartz rock. About four miles from 
Pittsfield, in the S. W. part of Hinsdale, are large rocks 
composed of variously shaped, not rounded, fragments of 
quartz cemented generally by fibrous brown Hematite. The 
iron ore is sometimes a mere lining of the fragments and 
sometimes nearly half an inch thick. It has very much 
the appearance of having been subjected to a high tempera- 
ture. Some have thought they discovered indications of 
an expired volcanoe. ‘This is doubtless mere imagination. 
In Great Barrington and Sheffield, the fragments are ce- 
mented by a quartzose cement. 
6. PRIMITIVE ARGILLACEOUS SLATE.* 
Colored Blue. — 
This rock is found along the foot of the hills ofthe Taconick 
range of mountains. In Williamstown it forms considerable 
* | have called this rock primitive argillite, because it is associated and 
alternates with primitive rocks, and is destitute of organic remains. There 
seem to be conclusive reasons against the removal of this rock from the 
primitive class,as Bakewell has done. His great reason for doing this 
is, that as some argillite contains organic remains, no argillite can be prim- 
itive. But while argillite is found in the primitive rocks, and alternating 
with some of them, (Cleaveland’s Min. and Geol. p. 449 and 740,) there 
must be the same reason for considering it primitive, as for ranking some 
kinds of limestone, greenstone, serpentine, &c. among minerals of the 
primitive formation. To remove all argillite into the fransztion and secon- 
dary rocks, istoblend the different rocks, and make the divisions, so gen- 
erally adopted, without the least use. The writer on organic remains in 
