THE NONMETALLIC MINERALS. 317 



being the representative features of the formation. To the west of 

 Gouverneur, extending to and beyond the St. Lawrence River, the 

 Potsdam sandstone is encountered; to the southeast, the Trenton lime- 

 stones extend toward the Adirondack Mountains. The talc belt is 

 found in the towns of Fowler and Edwards, from 7 to 14 miles south- 

 east of Gouverneur. It has a length of about 8 miles, a width of 1 mile, 

 more or less, and crosses the above-named Azoic island in the general 

 direction of WNW. to ESE. The "veins" generally dip from 45 to 

 75 toward the northeast. Their width varies from a few inches to 20 

 feet or more. Surface out croppings are frequent, and local experts 

 contend that there is no use in looking for talc where it does not appear 

 on the surface. The abrupt change of formation precludes the prob- 

 ability of discovering new deposits beyond the small, and now most 

 thoroughly explored, belt already known. Within this narrow terri- 

 tory, "veins" of talc minerals, separated by layers of granite and 

 gneiss, are found and worked. They are principally made up of the 

 hydrated silicates of magnesia, known as agalite and rensselaerite, the 

 former of a smooth, fibrous texture, the latter scaly and lamellar, and 

 both beautifully white or bluish-white. In the agalite veins are found 

 nodules of handsome pink to purple, columnar crystals of hexagonite, 

 and also large "horses" of yellowish- white hornblende. The occur- 

 rence of the two latter minerals, representing the anhydrous silicates 

 of magnesia, has given rise to the theory that the talc deposits origi- 

 nally occurred as hornblende, which has gradually become hydrated. 



Since 1879, ten distinct mines have been opened, and some of these 

 have reached a depth of 400 feet or more on the slope. The present 

 output from these ten mines amounts, according to a close estimate, to 

 51,000 tons a year, which figure, however, could be readily doubled if 

 the reducing mills had the capacity to handle the larger quantity. 

 (Specimens Nos. 53590 to 53592, U.S.N.M., from Gouverneur are 

 characteristic.) 



In western North Carolina and northern Georgia, particularly in 

 Cherokee, Moore, Guilford, and Murphy counties in the first-named 

 State, and in the Cohutta Mountains of Murray County in the last, are 

 numerous beds of very clean white or greenish fibrous talc occurring 

 in part, at least, in connection with the marble beds. Some of the 

 material is soft, white, and almost translucent (Specimens Nos. 26137, 

 27654, 63448, U.S.N.M.), while other is tough and semitranslucent, 

 hornlike. The beds are mostly very irregular in extent as well as in 

 quality of material. 



In Stockbridge, Windsor County, Vermont, talc is mined from veins 

 from 3 to 12 feet in width in soapstone. (Specimen No. 53206, 

 U.S.N.M.) A greenish schistose talc is also mined in Murray County, 

 Georgia, (Specimen No. 53226, U.S.N.M.) 



Soapstone occurs mainly associated with the older crystalline rocks, 



