I92I. No. 8. ox THE FXLOGITES OF NORWAY. 73 



In the specimens showing rather coarse plagioclase rods in the symplec- 

 tite an incipient amphibolitization may often be observed. This alteration 

 begins from the kelyphite rings and developes further along the boundaries 

 between the diopside-grains. Its effect is to produce a granular mass of 

 plagioclase and green hornblende, in which biotite may also be present. 



We have above taken examples of the diflferent stages of the re- 

 crystallization from various localities, as they presented themselves during 

 the work. To prevent misunderstanding, it must be pointed out that all 

 the stages were also found in rocks from a very limited area in Almklov- 

 dalen, and the}' are no doubt to be found at every occurrence of eclogite, 

 as well as also the further alteration into amphibolite. 



The diopside-plagioclase-symplectite is doubtless widely distributed in 

 the eclogites, although verv few petrologists have been aware of it. 

 F. Becke' first noted it from the Poorest region of Lower Austria, 

 and gave an exact description of its characters. 



P. Lohmann- observed the zones of alteration around the pyroxene in 

 manv eclogites and also in some specimens from Norway, but he did not 

 determine its components. 



A. Lacroix ^^ described the alteration of clinopyroxene into an inter- 

 growth of hornblende and plagioclase in eclogites from Loire i n f é r i e u r, 

 very like that which we, in the Norwegian eclogites, will find as a further al- 

 teration of the diopside-plagioclase-symplectite. Later S. Franchi"^ found an 

 analogous phenomenon in eclogites and eclogitic micaschists from the region 

 of B i el la and called it feldspar-uralitization. It seems probable to me that 

 many petrographers, after these observations, have taken pyroxene in 

 the finest intergrowths for amphibole. I have a specimen of eclogite from 

 Saint-Philbert de Grandlieu, Loire inférieure, in which pyroxene- 

 plagioclase-symplectite occurs exactly in the same manner as in the Nor- 

 wegian examples in its moderately advanced stages. 



Laura Hezner^ described, in great detail, the development of turbid 

 border zones in the eclogite-p^TOxenes of Sulztal and their alteration 

 into an intergrowth of hornblende and plagioclase. It is said that the host- 

 mineral, in the coarsest varieties, 'may be determined as hornblende and, 

 concerning the finest, dusty-looking portion, it is added: "Sehr feine Stellen 



I Loc. cit. (T. .M. P. M. 18821. 



- P. Lohmann, Neue Beiträge zur Kcnntniss des Eklogits vom mikroskopischen, mineralo- 

 gischen und archäologischen Standpunkt. N.J. f. Min. etc. 1884. 



3 A. Lacroix. Etude pétrographique des eclogites de la Loire inférieure. Bull. -Sei. Nat. 

 del'Ouest de la France. 1891, I, p. 8r 



^ S. Franchi, Ueber Feldspaturalitization der Natron- Thonerde-Pyroxene aus den cklogiti- 

 schen Glimmerschiefern der Gebirge von Biella iGraiische Alpen I. N. .1. Min. etc. 1902, 

 II, p. 112. 



^ Loc. cit. (T. M. P. .M. 1903. p. 451 and 5071. 



