211 
Fresh olivine has not been found, but the rock abounds in 
pseudomorphs which may with certainty be referred to this 
mineral, owing to the fact that the alteration has begun in the 
same way as in the essexite, viz. by the formation of a 
zone of iron-ore round the grains and along their cracks. 
The interior of these pseudomorphs consists of a greenish 
serpentine aggregate crowded with numerous small needles of 
actinolite. 
The augite is partly fresh and of a pale reddish violet 
colour. The extinction-angle с:с is about 45°; it is slightly 
greater for a blue than for a red light. The mineral is quite 
allotriomorphic, moulding the tabular felspar-crystals. It has 
originally been present in about the same amount as the oliv- 
ine but the augite-anhedra have to a great extent been con- 
verted into a greenish fibrous hornblende whose fibres are 
about parallel to the vertical axis of the augite. This uralitic 
hornblende is rather impure being full of small grains of iron- 
ore and of a strongly refringent mineral with high interference 
tints, perhaps titanite. The conversion of the augite is no 
doubt due to contact-metamorphism; yet in the most intensely 
altered portions of the rock (viz. those nearest the augite- 
syenite) there is no uralite left, but the rock is full of small 
grains of newly formed augite and scaly yellowish brown mica. 
The felspar is in tabular crystals giving sections of about 
1 millimeter in length by 01 millimeter in breadth. The de- 
composition-product is a colourless muscovite-like aggregate. 
Those parts of the felspar-crystals that are not decomposed in 
this manner are perfectly clear and fresh, a sign that the alter- 
ation of the rock is not due to ordinary weathering. The clear 
felspar has a faint brownish tint which is not due to visible 
inclusions of any kind; the outer zone of the crystals is, how- 
ever, usually colourless. The crystals are always twinned ac- 
cording to the albite-law and sometimes also pericline-lamellæ 
are seen, Carlsbad twins are frequent. In a number of sym- 
14* 
