

Washington — Study of the Glaucophane Schists. 35 



Art. III. — A Chemical Study of the Glaucophane Schists ; 

 by Henry S. Washington. 



Introductory. — Among the metamorphic rocks the glauco- 

 phane schists are of special interest, on account of their 

 peculiar mineralogical composition, as well as their compar- 

 ative rarity. It is therefore somewhat remarkable that they 

 have been only slightly investigated from a chemical point of 

 view, especially as the characteristic mineral, glaucophane, 

 has been analyzed from most of the localities. Indeed, as 

 Rosenbusch* has remarked, our knowledge is far from suffi- 

 cient for a proper understanding of their relations and origin. 

 It is with the object of supplying partially this deficiency that 

 the present chemical investigation has been undertaken. To 

 supplement the analyses, some petrographical description is 

 added, but the geological relationships will be only lightly 

 touched upon, on account of the lack of opportunity for 

 personal observations. 



The material from Syra was collected by myself, several 

 years ago, during a day's stay on the island. For the num- 

 erous specimens from the other localities I am deeply indebted 

 to petrographers in different parts of the globe, and I gladly 

 take this opportunity to express my hearty thanks to those 

 mentioned in subsequent pages, in connection with the various 

 specimens, for their kindness and generosity, which have made 

 this investigation possible by supplying me with the requisite 

 material. 



Syra, Greece. 



The glaucophane rocks of this island were first noticed by 

 Virlet,t in 1833, who took the blue hornblende to be in part 

 cyanite. Fiedler $ in 1841, in a sketch of the geology and 

 archaeology of the island, refers to this mineral as a horn- 

 blende, and mentions the abundance of epidote. Glaucophane 

 was indentified as a new mineral in these rocks by Hausmann § 

 in 1845. The rocks of the island were described by Lue- 

 deckeTf in 1876, from specimens collected by Fouque and von 



*Rosenbusch, Elemente der Gesteinslehre, 1898, p. 521; also Sitzungsber. 

 Akad. Wiss. Berlin, 1898, p. 706. 



fVirlet, Exped. Scient. de Moree, vol. ii, p. 66, 1833. 



^Fiedler, Reise durch G-riechenlatid, vol. ii, p. 168, 1841. 



§ Hausmann, Gott. gel. Anzeigen., 1845, p. 193, Ref. in Neues Jahrb. 1845, p. 

 321. 



^[ Luedecke, Zeitschr. d. deutsch. geol. Gesellsch., vol. xxviii, p. 248, 1876. 



