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Report of the State: Geologist. 



Report on the Talc Industry of St. Lawrence County. 



By C. H. Smyth, Jr. 



In a previous report the author had given some consideration to a certain 

 portion of the talc deposits in this region. A fuller account of the talc, its 

 nature, occurrence and exploitation is here presented. The deposits of this 

 mineral are largely in the towns of Edwards and Fowler. It may occur at 

 several horizons in beds of considerable thickness, and it is evident that these 

 beds are intimately related to the crystalline limestones with which they are 

 associated. The walls of these talc beds consist of a tremolite rock passing 

 gradually into the limestone, and one evidence that the talc is derived by 

 gradual alteration from the tremolite is the fact that much of the mineral is 

 distinctly fibrous, a condition of first importance to the economic applications 

 of the talc The soft, .scaly, non-fibrous talc is regarded as the ultimate 

 condition of the mineral resulting from the continuation of the decompo- 

 sition of the tremolite. Some account of the number of mines is given, 

 followed by a description of the process of manufacture, and some discussion 

 of the value of variations in physical character of the mineral, and finally a 

 statement of its uses in manufactures. 



Report on the Crystalline Rocks of St. Lawrence County. 



By C H. Smyth, Jr. 



This is an account of work done in this county in continuation of obser- 

 vations already made in a previous report. The townships whose geology is 

 especial!)' considered are those not canvassed in the previous survey by the 

 author. The principal purpose of the work has been to determine the distri- 

 bution of the crystalline limestones, for w hich the writer had already intro- 

 duced the term, " Oswegatchie series; 11 and, also, to collect data bearing upon 

 the question of the origin of the gneisses and the relation existing between 

 these rocks and the limestones. The limestones occur principally in belts, as 

 well as in small scattered patches. The extent of these limestone areas is 

 described, and in the same connection the areal distribution of the gneisses. 

 Three or four distinct belts of limestone are defined, together with smaller 

 accessory areas. The limestones are highly crystalline, with a considerable 

 range of color, and carry masses of embedded silicates, among them tremolite 



