GEOLOGY AND ORE DEPOSITS OF SU- AN 17 



rearrangement to suit the new chemical equilibrium. The present 

 rock may have been anamorphosed in such a way together with 

 the intruded rock — the slaty mica-schist which should have been 

 submerged deep into the zone of rock-flowage. Another fact may 

 be brought into harmony with the above-mentioned and this is, 

 that the contact-metamorphosed deposit, in which the present 

 complex of mica-slate forms the recipient of ores, is commonly 

 supposed to have been developed only in the zone of rock-flowage, 

 though the contrary has been recently asserted by Chas. R. 

 Keyes^\ 



The sedimentary metamorphics — of which brief descriptions 

 have been given in the foregoing, especially of chlorite-schist, slaty 

 mica-schist, clayslate, calcareo-siliceous slate, and the apparently 

 interbedded, two zones of limestones — all together constitute the 

 foundation of the region, the strike being W. N. W. and the dip 

 N. E. The age of the complex cannot be fixed exactly ; but from 

 the analogy of its occurrences in Manchuria (the pre-Cambrian, 

 Taku-shan series) and in Japan (the Sambagawan), the writer 

 provisionally assigns the complex to the same time-scale as the 

 pre-Cambrian, though it resembles in pétrographie characters the 

 Bündnerschiefer in the Alps, which embraces all rocks from the 

 Trias to the Cretaceous, and even up to the Eocene ~\ 



At the hill range rising due south of the mine, and farther 

 south in the valley of Morai-chhi, the coarse porphyritic granite 

 with the three-centimeter megaphenocrysts of orthoclase, is seen 

 exposed, culminating in the latter in the rugged peak of Ön-jin- 



1) Economic Geology, Vol. IV., p. 365. 



2) Lorenz, " Geologische Studien im Grenzgebiete zwischen Hervetischer und Ostalpiner 

 Facies." Die Berichte der nalur-forscher Gesell, zu Freiburg in Bres. Bd. XII., S. 4. 



