64 ECONOMICAL MINERALOGY. 



to the common or impure variety, being mixed with carbonate of hme 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, 1 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 hiineralogist. 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.! 



Oneida County. Gypsum is foimd here in beds of vast extent. It is often foliated and 

 transparent ; but the largest proportion is of the impiure 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 efiervesces freely in acids, and contains variable proportions of the oxide of 

 iron. Gjrpseous beds, similar in their general characters, also occur in the vicinity of Man- 



 Hall. New-York Geological Reports, 1838. 



t Mr. Hall thinks that hundreds of quarries of plaster'might be opened along the line of the limestone terrace, from Black-Rock 

 eastward. Neu-York Geological Reports, 1841. 



