194 



and poorer in large magnetite masses appeared to mj surprise to be 

 made up of the ordinarj- antigorite-serpeiidiie with so-called olivine- 



4 







Fig. 2. Same as fig. 1, in polarized light with crossed Nicols. 



rests. It appears to me that the cross-grained structure in those 

 serpentines and the fine grain are caused by rapid cr^-stallization. 

 Also in these specimens the olivine is quite fresh. 



The sequence of cristallization as manifested in the slides is the 

 following: 



Antigorite ; antigorite-magnetite ; antigorite-olivine-magnetite. 



To all appearance the latter combination is a eutecficum, 

 although it is not impossible that the magnetite is resorbed later. 



Since the rock lies near the surface, the conditions for serpenti- 

 nization by meteoric agencies have been favourable. However, of 

 this the rock does not present any recognizable trace. The question, 

 therefore, urges itself upon us whether the serpentine might perhaps be 

 always of a magmatic origin, at all events not a product of weathering. 



Now, as to the genesis of this rock we may broach the supposi- 



