418 
GEOLOGY OF THE SECOND DISTRICT. 
CHAPTER XI. 
Some of ihe common substances which may be employed foi' economical purpjoses. 
Economical materials existing in the form of rocks. 
Mantels, Centre tables, etc. Hypcrslhene rock, forming in many instances a beautiful 
material in which the elements are homogeneous, or combined with great equality, may with¬ 
out doubt be manufactured into the richest and most durable patterns for mantel pieces and 
ornamental tables of various kinds. In this rock there are several varieties^ which differ in 
color principally as it regards a light and dark ground, and the distribution thereon of crystals 
of labradorite. The varieties with a light ground are generally opalescent, or at least this 
quality appears in them to better advantage than in those with a dark ground, in which the 
opalescence is observed with difficulty. There can be but little doubt but that this material can 
be obtained in a form and condition which will meet with a sale. Mr. Henderson, while 
superintending some improvements in the reduction of iron ore, placed a block of hypersthenc 
so as to be acted upon by a short common saw which was moved by the machinery of a mill, 
and found that it cut into the block to the depth of two inches during the day. At that rate, 
a gang of saws would in a short time cut out slabs suitable for tables or mantel pieces of the 
ordinary size. Should these opinions be found correct, after some farther experiments, one 
more source of private enterprise will be opened. This rock is confined to Essex county. 
Lime, and Mortar. I have ascertained that limestone exists in all parts of the district; and 
I am of the opinion that it may be found, if not in every township, at least within a short 
distance therefrom. It was made a special object of search wherever I went. Some diffi¬ 
culty, however, was experienced in finding it in the wooded and unsettled districts. It rises 
in the midst of the hypersthene rock, in the form of beds or veins ; and it is common in the 
granite and gneiss districts, in the same condition. Hence there will be an abundant supply 
of lime for mortar, and for agricultural and domestic purposes. The primary limestone is 
rarely suitable for any other purpose than the manufacture of lime, for it is too liable to dis¬ 
integration to be used as a marble or building material. The Champlain group furnishes 
several limestones suitable for marble. The rock beneath the trenton occurs at several places, 
and also the thick layers of the birdseye upon the Great bend of the Black river, and at Chazy. 
