Geology, $c of the Connecticut. 215 
inches in diameter, the outer extremity of which presents 
the form of the prism. Iam rather disposed to believe that 
these cavities were once filled by a mineral not differing 
much from the Thomsonite of Dumbarton in Scotland. 
ome varieties of quartz occur along the primitive region 
of the Connecticut that can hardly be referred to any of the 
preceding. ‘Thus, there isa variety very abundant in beds 
and tuberculous masses in mica slate and argillite, which 
differs in nothing from limpid quartz, except that it is color- 
ed crimson red ; and perhaps it ought to be referred to fer- 
reinots quartz; but it differs from that commonly so cal- 
ed. 
black, and only semi-transparent. Another variety has a 
tinge of yellow—another of green, &c. 
16. Amethyst. At Wallingford, Farmington, Berlin and 
East-Haven. Aijso at Mount Tom in East-Hampton. (Sil- 
liman,) Also in greenstone, Deerfield, forming geodes of 
a light purple; crystals from one tenth of an inch to an inch 
indiameter. Also in Westminster, Vermont, in crystals an 
inch and an half in diameter. 
17. Ferruginous Quartz. At Litchfield. (Brace.) 
18. Fetid Quartz. I have recently found this in several 
laces, from Woodbridge, near New-Haven, to Bellows- 
Falls in New-Hampshire, a distance of one hundred and 
fifty. miles, in loose rolled masses. In the vicinity of Con- 
Way it is very abundant, and occurs crysta!lized in the com- 
mon six-sided prisms ; which are sometimes so flattened ae 
to be three times as broad as thick. In Conway it occurs 
in veins in mica slate and granite ; less fetid, however, than 
that which is found loose on the surface. It is traverse 
by thin seams, or veiis, apparently ferruginous; its color is 
nearly milk white and its lustre a little resinous, In some 
specimens the fetid odour is very strong. 
