1 92 1. No. 



ON THE ECLOGITES OF NORWAY. 



83 



rock exhibits much mechanical deformation, a common phenomenon in the 

 Sogn labradorite-rccks (cf. J. Rekstad and V. M. Goldschmidt, op. cit. I. 



The inner portions of the inclusions consist almost exclusively of 

 olivine as a millimeter-grained mass. Cracks in the crystals are filled up 

 with pigmentary black substance together with some brown serpentine. In 

 making separation with a heavy solution this dark substance was concen- 

 trated in portions less heavy than the clean olivine. By a chemical test 

 the mineral was found to be serpentine mixed with iron ore. 



The specific gravity of the olivine was found to be 3.54, which should, 

 according to a graphical interpolation from known values, correspond to 



Fig. 12. Schematical view of the inclusions. Black is olivine, surrounded by successive zones 

 of anthophyl'ite and hornblende with garnet (dotted 1. 



about 22 ^ FeO. The optic axial angle is so near 90 that the optic 

 character only with difficulty can be determined as negative. This also conforms 

 to a composition with about 22 '^ FeO or Fa._,_^Fo-e. ,3 = 1.705 ± 0.00 1, 

 from which results the composition Fa.^jFo-^. 



The olivine-rock is surrounded b}' successive zones of anthophyllite 

 which, in the inner zone, is a fibrous, asbestos-like \ariety and, contrary 

 to the anthophyllite in the labradorite-rcck, colourless in thin section. Its 

 fibres are always arranged perpendicular to the zones. I determined 

 Y = 1.645 àz 0.002. If this is a non-aluminous anthophyllite, as would seem 

 probable from its large positive acute axial angle, its composition might be 

 interpolated from the values in the anthophyllites from Franklin and Kongs- 

 berg (Rosenbusch-Wülfing, Mikr.Phys. i, 2-, p. 153 1 at about 12 "^O FeO 

 and 27 ^ IMgO. 



