Cyanite from a Neio Locality. 



201 



net, cyanite, tourmaline, and other heavy metamorphic minerals 

 are heat, moisture, and high pressure; that they are produced 

 by processes of silication, and are formed normally in the zone 

 of anamorphism. Emmons* adds rutile to the list of those 

 minerals sometimes formed under conditions of dynamic 

 regional metainorphism. Following Emmons f and Lind- 

 greu^: in the genetic classification of minerals, garnet, rutile, and 

 tourmaline are regarded as occurring under igneous conditions, 

 in pegmatite veins, in contact metamorphic deposits, in deep 

 vein zones, and under conditions of dynamic regional meta- 

 morphism. Cyanite is not known to occur as a pyrogenetic 

 mineral nor as a product of the deep vein zones. In the area 

 described cyanite is regarded as having formed contemporane- 

 ous with the metamorphism of the rocks. 



The rocks of the small area described are metamorphic crys- 

 talline schists derived from original sediments under anamor- 

 phic conditions and the area so far as known is removed from 

 igneous rocks and therefore from igneous contact positions. 

 Pegmatites and veins are not known to occur. The heavy 

 metamorphic minerals are regarded, therefore, as having b een 

 produced under conditions of dynamic regional metamorphism. 



Brooks Museum, 



University of Virginia. 



* Emmons, W. H. Economic Geology, vol. iii, p. 621, 1907. 



t Emmons, W. H. Ibid., pp. 619, 621, 622. 



% Lindgren, Waldemar. Ibid., vol. ii, pp. 122-125, 1906. 



Am. Jour. Sci. - 

 15 



-Fourth Series, Vol. XXXII, No. 189.— September, 1911. 



