242 Prof. Bonney : Penological Notes on the Eupholide 



scopic examination to be really composed of an aggregate of 

 minute crystalline grains, which, however, in certain cases, 

 show signs of orientation. Now and then traces of an old 

 cleavage with a diallage-habit may be detected ; in other cases 

 these are distinct and extinction with them ranges up to about 

 40°, but the grains are interstreaked, pierced, or sometimes 

 traversed by zones (as if filling cracks) of a nearly colourless 

 mineral resembling actinolite, and extinguishing at angles less 

 than 20°. In other cases the smaragdite occurs in grains, almost 

 colourless in thin slices, which sometimes show the charac- 

 teristic cleavage of hornblende, and give its extinction-angle, 

 but occasionally the latter indicates that an augite (omphacite) 

 is also present*. 



The green hornblende in (4) is often bordered by a pale 

 fibrous actinolite, and sometimes by well crystallized pale- 

 coloured hornblende ; but the greater part of the patch 

 retains traces of a former close cleavage as above described, 

 but now consists of a rather fibrous pale green hornblende, 

 which, though composite in character, exhibits a rudely 

 parallel orientation, the whole being much clouded by dusty 

 lines and patches. High powers show many of them to con- 

 sist of minute belonites, and here and there needles of rutile 

 can be identified. This form is also found in some of the other 

 varieties of the euphotide, e. g. together with the " slate-blue " 

 hornblende of (2). Here it is rather " muddy " looking, 

 containing minute enclosures and tiny brown films ; the 

 microliths by their general orientation seem related to some 

 occasional faint lines, which may be indications of a former 

 cleavage : the films may be traces of " schillerization." 



The " slate-blue " hornblende in (2) occurs in " nests " of 

 irregular form, roughly resembling sections of amygdaloids in 

 a scoriaceous rock. It is sometimes idiomorphic, sometimes 

 rather fibrous in structure and irregular in shape. It varies 

 from colourless to a very pale blue, and is not strongly 

 dichroic, changing in longitudinal sections from almost 

 colourless to a pale violet-blue, in transverse sections from 

 bluish to a faint purple. Evidently it is one of the paler 

 varieties of glaucophane f . The mineral usually is fairly free 



* I have seen the mineral with characteristic augite cleavage in some 

 smaragdite rocks, but do not find a thoroughly satisfactory specimen in any 

 of my slides from the Saasthal. 



t It may he interesting to mention that a glaucophane-eclogite is far 

 from uncommon in the boulders of the Saasthal. Here the mineral is 

 richly coloured. I have not found the rock in situ, but have no doubt it 

 is from some part of the range which extends from the Strahlhorn to the 

 Egginerhorn. Most of this is a green schist with garnet, hornblende, &c 

 and it contains, certainly sometimes, probably often, glaucophane. 



