588 



So we can distinguish near the contact of the granites successively: 



1. A qiiartz-tourmaline zone of varying thickness (sometimes not 

 thicker than a few mm., somelimes entirely missing). 



2. A qnartz-miiscovite zone with lourmaline, of some cm. 's breadth, 

 which is most times missing. • 



3. A qiiartz-biotile zone which also occurs at the very contact 

 of the granites. 



In the qiiartz-tourmnline zone — partly perhaps a marginal facies 

 of the granites — .sometimes plenty of garnet and often in small 

 quantity some muscovite and apatite occur together with the main 

 constituents. The structure is sometimes beautifully poikiiitic, larger 

 lourmaline crystals, sometimes reduced to skeletons, enclosing numerous 

 grains of quartz and sometimes also cr^'stals of garnet and smaller 

 crystals of tourmaline. This zone often shows a mosaic structure, 

 which sometimes approaches to the hypidiomorphic granular structure, 

 these various structures graduate into each other, and in the granular 

 mixtures we sometimes see some larger crystals of tourmaline 

 with poikiiitic structure. Again, the garnet often encloses small quartz- 

 crystals, even when it is itself enclosed liy tourmaline. Often this 

 mineral is troubled by numerous inclusions, partly vei'y fine ore-spots. 

 Occasionally, some irregularly limited and turbid felspar was 

 observed in this zone, which poikilitically enclosed quartz and also 

 muscovite. Between the granites and the quartz-tourmaline zone a 

 strong contrast can be seen microscopically, due to the differences 

 of structure, size of grain and constituent minerals. Between the 

 quartz-tourmaline zone and the granites sometimes a narrow zone 

 is observed, consisting of an aggregate of quartz-crystals only or 

 of quartz-crystals intermixed with very little tourmaline and musco- 

 vite or of a quartz-muscovite-mixture with much muscovite. 



The (jU(i)-t:-inu.scovite-zone, which on several places was found 

 showing a thickness of some mm. only, between a quartz-tourmaline 

 zone of the same thickness containing much garnet and some mus- 

 covite and a qiiartz-biotite-zone containing less garnet, insensibly 

 graduates into the adjoining zones. In the quartz-muscovite zone 

 tourmaline-crystals still occur, which farther from the contact disappear 

 almost entirely. By the growing intensity of a brown colour, the 

 muscovite graduates farther from the contact into a pale brown mica. 

 The percentage of garnet is much smaller than in the quartz-tuur- 

 maline-zone and it remains almost constant in the quartz-biotite-zone. 



The qmu'tz-biotite-zoiit' contains mostly tourmaline, sometimes 

 muscovite and garnet. As a rule the quartz-tourmaline zone is between 

 it and the contact, occasionally it also occurs at the very contact of 



