Geology and Mineralogy of a part of Massachusetts, &c. 15 
exquisite polish, have been found, which are supposed to 
indicate a superior quality of marble ata greater depth. 
It is a common remark of the workmen, that the quality 
improves as its depth increases. 
The elastic marble of Lanesborough and West-Stock- 
bridge has long attracted the attention of mineralogists. 
The artificers consider it a poorer kind of marble, less 
compact and fine; and some of them have made the re- 
mark that most of their coarser marble is somewhat elas- 
tic. 
The value of the marble annually wrought in the coun- 
ty of Berkshire, is estimated at about $40,000. Travel- 
lers who have not been accustomed to such abundance of 
this beautiful mineral, have often admired the multitude 
of white marble monuments in our church-yards, and ex- 
pressed their surprise at its commonness in ordinary 
dwelling houses. 
Where the limestone joins the mica slate, the two often 
run into each other, forming, with the quartz and some- 
times talc mingled with it, a singular aggregate, scarcely 
capable of being named, and not worth the trouble of do- 
ing it. Near Williams College, is a bed of limestone 
which contains a large proportion of quartz. It is a fine- 
grained, compact mineral, harder than the true granular 
limestone, and sometimes much divided by irregular seams 
which are lined with tale. This bed may be traced for 
ihe distance of two miles—white and gray —and often di- 
vided by natural seams into rhomboidal masses of various 
dimensions. 
‘Caverns are said to be uncommon in granular limestone. 
In this section, however, are several. They are at Ben- 
nington, Adams, Lanesborough, West-Stockbridge, and 
New-Marlborough. The walls are covered with semi- 
crystalline calcareous incrustations; and stalactites and 
stalagmites, are found in them. ‘The caverns at Benning- 
ton and New-Marlborough, have several rooms, some of 
which are large. That at Lanesborough is a long and 
harrow cavern, which appears to have been formed by a 
subterraneous stream of water, which has probably found 
a passage at a lower depth. 
The granular limestone alternates several times in this 
section with mica-slate. The alternations in Salisbury, 
Con. were noticed by Prof. Silliman, Am. Journ. Vol. II. 
p> 211. 
