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2. Mention may, in connection with granite, be here 
introduced of a specimen from a granite dyke in the island of 
Arran, N. Britain, which on account of its intrinsic value, merits 
attention, as it is an instance of a granite penetrating and 
throwing off branches into another granite, or it may be diorite, 
the interpenetrating rock must have been in a molten state, 
and affords a characteristic example of contact-metamorphism. 
This rock exhibits a burnt or charred state under natural con- 
ditions. The striking point in it, is that we can note the effect 
of long cooling down from a high temperature throughout a 
long period of geological time. 
At Tornidneon, in the island of Arran, the granite veins 
run into the body of a very coarse granite—strings of the finer 
grained rock traverse the coarser grained one. Bands of a 
black Pitchstone, a vitreous state of granite, also penetrate the 
igneous rocks in Arran. The hand specimen of the charred 
granitic rock mentioned above, displays a structure entirely 
granular, the smaller felspar resembles dark round grains of 
gum arabic, the colour of the whole piece is a brown black, in 
hue and aspect very nearly like the burnt granite of Newnham 
Church. 
Rosenbusch cites (i. page 45, 2nd edit. 1886) Mic’ nel-Lévy 
in a useful description of a similar contact phenomenon of a 
eranulite occurring at Morvan in Brittany. 
An approach must now be made to the alteration at higher 
temperatures, viz: at the fusion point of some rocks closely 
related to granite; these are granulites, and will bear illustra- 
tion, drawn from several well-known sources, visited by the 
author. 
II. GRANULITES— 
Granulite (Weiss). These granitoids are the Leptinite 
(Haiiy) of French petrographers, and are altered eruptives 
formed of débris, in nearly equal proportions of quartz and 
felspar, generally cemented together by a more recent quartz, 
which has had a tendency to crystallise in somewhat granular 
hexagons of an irregular contour. It must be remarked 
emphatically, as it is an essential point insisted on by Haiiy 
