64 
ECONOMICAL MINERALOGY. 
to the common or impure variety, being mixed with carbonate of lime and clay. It occurs 
imbedded in gypseous marl, every where forming irregular or somewhat rounded conical 
masses or hillocks, rarely more than forty or fifty feet in diameter, and usually from ten to 
twenty feet in height. The masses of gypsum are a foot or more in thickness, and weigh 
from four to six hundred tons. I can give no details concerning the amount of this mineral 
annually raised in this county ; but in 1837, I was informed that in the town of Sullivan alone 
there were raised from four to seven thousand tons annually. 
Monroe County. Several specimens of foliated gypsum, of a rose colour, were found 
below the Falls of the Genesee at Rochester, many years since; and nodules of the snowy 
variety occur in the limestone at the same locality. Gypsum is also obtained in small quan¬ 
tities in the towns of Pittsford, Riga and Chili; but according to Mr. Hall, the workable beds 
of this mineral are almost wholly confined to the southern part of the county. “ Along the 
valley of Allen’s creek and Mill creek, two miles north, most of the plaster of Monroe county 
is obtained. Both these places are in the town of Wheatland. About 5000 tons of gypsum 
per annum are obtained from this town ; of this quantity, 4000 tons are used in this county.”* 
Niagara County. The localities of the hydrous sulphate of lime in this county are of 
considerable interest to the mineralogist. At Lockport, beautiful specimens of transparent 
selenite and snowy gypsum have been found, associated with calcareous and pearl spar, sul¬ 
phate of strontian, and the rare anhydrite or anhydrous sulphate of lime. Snow-white gra¬ 
nular gypsum also occurs near the Falls of Niagara, with occasional specimens of foliated 
selenite of a bluish colour. At all these localities, the gypsum is imbedded in the geodiferous 
limerock of Prof. Eaton; but it does not, so far as I am informed, occur in quantities suffi¬ 
cient for useful purposes.t 
Oneida County. Gypsum is found here in beds of vast extent. It is often foliated and 
transparent; but the largest proportion is of the impure kind, mixed with carbonate of lime. 
This last, however, is almost equally valuable for agricultural and other purposes. 
Onondaga County. The interesting region around Onondaga lake contains, in addition to 
its other sources of wealth, some important deposits of gypsum. At Liverpool, the fibrous 
variety, then comparatively rare in this State, was found several years since, about twelve feet 
below the surface of the earth, associated with marly clay. The excavations made for the 
construction of the railroad from Syracuse to the Split Rock quarry, opened an extensive bed 
of the same mineral. At this locality are to be found several varieties; as the foliated, the 
fibrous, the snowy, and the common or dark coloured; the whole imbedded in a kind of gyp¬ 
seous marl, which effervesces freely in acids, and contains variable proportions of the oxide of 
iron. Gypseous beds, similar in their general characters, also occur in the vicinity of Man- 
* Hall. New-York Geological Reports, 1838. 
+ Mr. Hall thinks that hundreds of quarries of plaster might be opened along the line of the limestone terrace, from Black-Rock 
eastward. Neiu-York Geological Reports, 1841. 
