270 B. KOTÖ. 



presence, I think, I may discriminate this schist from allied micaceous 

 rocks. The tourmaline is of greijisli-hroum, or sometimes of greenisli- 

 hhie colour. 



(1) Of these the greyish-brown kind occurs in the form of 

 prisms with imperfect terminations, which enclose a large quantity 

 of the dust of iron glance. The mica occurring associated with this 

 variety of tourmaline is a hroim biotite in irregular lamelJœ, frayed 

 out at the margin into a felt-work of fibrous mass ; while the general 

 matrix in which it is imbedded is a mosaic of round grains of quartz. 

 There are other patches of much larger, angular interlocked quartz 

 forming irregular, sinuous bands in which biotite is proportionally 

 rare, while in the micaceous portion both muscovite and the brown 

 biotite are plentiful. The quartz is ideally pure, and in this point 

 the rock differs from those of the lower horizon. Round-edçfed 

 crystals of apatite are sporadically present. 



(2) The schist with a dirty hrowmsh-grcen biotite, of the same 

 habitus as the preceding, appears somewhat like a chlorite schist 

 and contains the prismatic, grecnish-hhie towimdinc which clusters 

 at some places into a confused aggregate, a peculiar habitus not 

 observed in the other mica-schist. Angular grains of feldspar are 

 found intermixed with quartz, which through weathering may 

 be readily distinguished from each other. The yellowish-brown 

 needles of rutile occur in the foliie of the biotite in divergent-radial 

 arrangement. Garnet, the commonest accessory, is, however, not 

 present in all the schists of this group. Lwi glance is always more 

 or less jn'esent, taking the place of magnetite in the other roclis, lying above 

 and below this one. 



C. Garnet-Chloritoid-Quartz-Schist. 

 Intercalated between the chloritic amphibole-schists of the upper 



