266 ROCK SPECIMENS COLLECTED IN NORWAY. Nov.. 1889. 
twinning of tlie felspar grains—I imagine probably due to 
pressure—but there has plainly been a certain amount of 
cleavage and slip among the grains. 
The flaggy gneissose or schistose rock from Yic, which Mr. 
Pumphrey informs me is used as slates in the district, would 
probably afford very much the same appearances modified by 
the fact of being made out of a more basic rock. 
Another specimen from which I have cut a section is that 
marked labradorite from the Nerodal—I think this should be 
called saussurite. It contains a few very shadowy grains of 
some plagioclase felspar, which still retain the twinning, 
but the greater part is made up of a mass of mostly interlaced 
crystals, very ragged at the edges, but apparently formed 
in situ. Some of these seem to extinguish when their 
length is parallel to one of the axes of the nicols prisms, but 
in rnanv the extinction angle is about 20°; there is also an 
indistinct cleavage in some of the larger grains, but as these 
seem to give brighter colours with crossed nicols, I imagine 
it may be another mineral which is present. In “ Teall’s 
Petrography,’ 1 under the head of saussurite, it is mentioned 
that this substance appears to be usually a mixture of some 
felspar with either zoisite or epidote. Catlirein, who has 
very thoroughly investigated the subject, considers that no 
distinction can be drawn between zoisite and epidote saus- 
surites. Dr. Beuscli has described a saussurite from near 
Drontlieim, which mainly consists of epidote either quite 
colourless or pale greenish yellow, and shows twinning. I 
think that the composition of the specimen on the table must 
be much like this, but I have not yet been able to refer to the 
original memoir. The mass has arisen by the decomposition 
of a highly basic lime felspar, the zoisite or epidote using up 
the lime. The specimen is quite different from the saussurite 
of the Lizard, which I show for the purposes of comparison. 
The latter has a much more granular structure. As Mr. 
Teall says:—“ Indeed it must be remembered that the term 
saussurite has no precise signification. It is merely employed 
to designate the dense light-coloured aggregates which arise 
in connection with the alteration of a basic felspar.” 
One or two other of the specimens should be noticed. 
One huge grained quartzite and one fine glistening one are 
completely analogous to two from the pebble beds of Sutton. 
The specimens of dolomite are particularly beautiful, 
both the snow white one and that which displays on part 
of it such a lovely rose tint. 
The soap stone of Drontlieim appears to be a sort of 
talc-mica schist with no very marked foliation. There are a 
