1 92 1. No. 8. 



ox THE ECLOGITES OF NORWAY. 



91 



In a monographical treatise C. F. Kolderup ' described tliis rock-series 

 in detail and cleared up the genetic relations. I take the lil)erty of ab- 

 stracting, from this memoir, some facts having special interest for our studv. 



The primary minerals of the labradorite-rock are plagioclase, garnet, 

 P3'roxene, biotite, ilmenite, magnetite, apatite and P3'rite, and the secondary 

 are rutile, hornblende, chlorite, muscovite and paragonite, epidote, zoisite, albite 

 and quartz. Garnet and biotite are also found as secondary products, but 

 the occurrence of primary garnet is regarded as an indubitable fact and as 

 being of great importance: "Dieser Umstand, die Granate als primär aufzu- 

 fassen, ist für die ganze Auflassung der Eruption der Labradorfelse von 

 grosser Bedeutung." (Op. cit. p. 19.) 



The plagioclase has the average composition AbjAn,, which is also 

 the average of all the analyzed rock-making labradorites in Norway. 



The garnet is, in the Bergen labradorite-rocks, of universal occur- 

 rence, partly evenly distributed and partly aggregated in dark lenticular 

 masses in which they either form a peripheral zone or a kernel. The 

 garnet is always isotropic. Its grains are surrounded by kelyphitic zones 

 of green hornblende. 



An analysis of garnet from labradorite-rock near Alvaerstrommen 

 (p. 32) may be quoted (the mol. numbers calculated by the present writer). 



RO : R,0.5 : SiO., -- 2.62 : 1 : 3.29 

 Composition : (Fe8gMgioCa.2.2)3(Alg.2Fe88)- 



Clinopvroxene is often abundant. An analysis of diallage from 

 labradorite-rock near Alvaerstrommen shows the following composition 

 (p. 28): 



1 Carl Fred. Kolderup, Die Labradorfelse des westlichen Norwegens. II. Die Labrador- 

 felse und die mit denselben verwandten Gesteine in dem Bergensgebiete. Bergens 

 Museums Aarbog 1903, N:o 12. 



