I92I. No. 8. ox THF KCLOt.lTES OF NORWAY. y I 



attain a breadth of o.i mm and the tlireads, which art- here seen to con- 

 sist of an individual, colourless birelVacting- mineral, mav be 0.005 ''■'"^i 

 thick and ha\-e curved forms, like the quartz-threads in the plagioclase- 

 quartz-myrmekite. The intergrowth is chiefly confined to the boundar^'- 

 lines, but at places these zones grow thicker and send out bavs into some 

 of the limiting pyroxene-grains. The ground-mass of the intergrowth may 

 here be determined as clinopyroxene, having the same réfringence as the 

 adjacent chloromelanite and a positive axial angle of about 60 . On the 

 boundary-line between two pyroxene grains, all the intergrown pyroxene 

 is individual and forms the continuation of one of the pyroxene grains. 



In another specimen of the chloromelanite-eclogite from Van el ven 

 the zones of intergrowth show a more decided tendency towards sinuous 

 development, and the rule was found to hold good that the sinuous portions 

 belong to those individuals from which they have grown out, and not to 

 those towards which their convex sides are directed. 



In a specimen from Langeland, Sun el ven, the sinuous inter- 

 growths occupy a large part of the pyroxene mass, in another marked 

 G urs kø (fig. -j, pi. II) almost a half. The intergrowth invariably is coarsest 

 at the basis of a sinus where its growth had started, and, towards its con- 

 vex margins, or the front of the gradually protruding sinus, it becomes 

 ever finer and, at the very margin, resumes the dustv appearance charac- 

 teristic of its incipient state. 



At this advanced stage zones of intergrowth frequently appear to have 

 begun to grow from the boundary line to each of the limiting individuals 

 and do not belong to any of them. Careful observation, however, shows 

 that thev then have started from some other neighbouring individual. 



In a specimen from Leinekixen, Boland, the intergrowth has re- 

 placed the greater part of the pyroxene (fig, 8, pi. III. 



The development of the secondary intergrowth was, in several speci- 

 mens, followed to even more advanced stages. The grains seem to eat 

 one another, the individualit}- of every grain becomes transported to some 

 of its neighbours, at the same time as the myrmekite-like intergrowth 

 developes. That stage, where no unaltered clinopyroxene was lelt, but 

 still no other change had been induced, was found almost attained in a 

 specimen from Saetre on Hareid (fig. 9, pi. II). As follows from the 

 mode of growth, an individual of pyroxene, at this stage, mostly limits by 

 its finest front side to the coarsest basis side of the adjacent indixidual. 



The "threads" or "rods" forming the minor part of the intergrowth, 

 attain, in the specimen from Leinekiven, a breadth of 0.0 1 mm. In réfrin- 

 gence and birefringence thev conform to plagioclase; no twinning was ever 

 observed. Within a definite individual of pyroxene all the rods belong to 

 one and the same individual of plagioclase. In their real shape they are 

 tabular and folded and not threads or rods, as they appear in thin 

 sections. 



