1921. No. 8. 



ON THE ECLOGITES OF NORWAY, 



35 



Or, tabulated in the usual way : 



Sp. 



3.61 (t = 12"). 



Auvergnose, III, 5, 4, 3. 



Disregarding the exceptionally high percentage of apatite this chloro- 

 nielanite-eclogite shows a typical gabbroic composition, though the ferrous 

 oxide is rarely found in such a large proportion to the magnesia. Yet 

 such rocks occasionally occur also in large areas with a great persistency 

 of the composition. We may mention the geologically well defined series of 

 so-called olivine-diabases in Satakunta in Finland and Nordingrå and Asby 

 in Sweden ^, the analyses of which we meet when seeking those nearly 

 identical to the above figures. These rocks are almost normative in their 

 mineral composition, belonging to the gabbro facies. In the amphibolite 

 faciès such a composition would probably give rise to a spinel-bearing 

 amphibolite or perhaps an olivine-amphibolite. 



The specimen of chloromelanite-eclogite studied was exceptionally un 

 altered. The grains of p3'roxene, however, are surrounded by zones of 

 myrmekite-like intergrowth of p3'roxene and plagioclase, 5.7 per cent of the 

 whole rock. It shows sharp boundaries towards the unaltered pyroxene. 

 A discussion of this kind of alteration follows on later pages. It is very 



' J. M. Sobral, Contributions to the geology of the Nordingra area, Bull. Geol. Inst. Uni- 

 versity of Upsala, XII, 19 13. 



