242 Carl Fred. Kolclerup. [Nr. 8 



céntric structure are seen in a granitic mass rich in quartz. (Fig. 79). 

 Green spinel is enclosed in the grams of ore, which are enveloped 

 by small aggregates of hypersthene with biotite, and uttermost by 

 hornblende. Also these norytes are garnet-bearing. 



Mangerites and closely Allied Rocks. 



The mangerites which occur in the cross-section Trengereid— 

 Vaksdal (CIII) are greyish medium -grained to fine-grained rocks, 

 which partly pass into uralitisized pyroxenites. Under the micro- 

 scope we see the following minerals: Zirkon, apatite, pyrite, 

 ilmenite, monoclinic and rhombic pyroxene, hornblende. garnet and 

 microperthite. 



The pyroxenites associated with the mangerites consist chiefly 

 of monoclinic pyroxene of poikilitic structure and plagioclase in the 

 cavities. These plagioclases are nearly parallel to the axis of the 

 pyroxene, which likewise have narrow ranges of grains of ore and 

 spinel. Some pyroxene is metamorphosed into the eommon bluish- 

 green hornblende. The brown hornblende often forms a rim 

 around the masses of iron ore, in which some green spinel is 

 frequently enclosed. Fig. 80 shows the structure to us; the dark 

 mass in the centre is constituted by ilmenite, and within this latter 

 there are smaller individuals of green spinel. Outside the ore we 

 have first a zone of brown hornblende and then one of plagioclase. 

 The right side of the slide is constituted by a poikilitic bluish-green 

 hornblende ; the rest is poikilitic pyroxene with plagioclase, ilmenite 

 and some spinel in the cavities. 



Birkremites. 



Birkremites and acid rocks related to them occur in several 

 places within the labradorite-rock-area of Storenuten. Within the 

 labradorite-rock-zone designated on the section Trengereid -Vaksdal 

 as XC VIII occurs a part of coarse-grained rock chiefly consisting 

 of a bluish-grey felspar and some irregularly dermed aggregates of 

 pyroxene and hornblende. The felspars are microperthite of some- 

 what various composition ; 2 /:: have a speciflc gravity = 2.61 and 

 Vs sp. gr. == 2.60. 



The birkremite in zone XCIX is a fine-grained rock of greyish 

 to reddish colour, chiefly consisting of quartz and microperthite, 

 but also holding small quantities of albite and orthoclase. The 



