﻿708 PROF. T. G. BONNET AND MISS C. RAISIN ON THE [Nov. I905, 



one place the two varieties form a nest in the heart of a grain of 

 diallage, piercing it in all directions irrespective of the cleavage. 



The second specimen, labelled in the field ' serpentine (streaky)/ 

 came from a block on the right lateral moraine of the Fee Glacier, 

 and is probably in situ somewhere near the Hinter Allalinhorn. 1 The 

 rock has been somewhat affected by pressure ; about four-fifths of 

 it (PI. XLV, fig. 5) is augite, clear to ' dusty,' 2 with only occasional 

 traces of diallage-cleavage, and the remainder (besides iron-oxide) 

 consists of the two mica-like minerals, the larger generally (though 

 not always) affording the yellow polarization-tints ; both, so far as 

 measured, giving straight extinction. They are intimately associated 

 with the augite, but their general direction is obviously at right 

 angles to that in which pressure has acted. 3 There is one grain, 

 about *06 inch long, which gives the dull but rich blue polarization- 

 tints already mentioned. 



The third specimen, from the terminal moraine of the same glacier, 

 may have come from either the above-named range or a spur running 

 northwards from the Allalinhorn to the Langenuh. The rock is 

 modified by pressure, and consists (besides iron-oxide) almost wholly 

 of a rather confused mass 4 of colourless mica-like minerals, which 

 afford both kinds of polarization-tints, the brighter on the whole 

 dominating, and both giving, so far as measured, straight extinction. 

 We find, however, some irregular patches of flakes, which have a 

 slightly-stronger cleavage, show a tinge of brown with transmitted 

 light, and are feebly pleochroic (very pale green with parallel 

 vibrations, and rather straw-coloured with perpendicular). 



The fourth specimen (labelled ' rather crushed ') is from the same 

 moraine, and is found to be (apart from the iron-oxide) a mass of 

 mica-like flakes, varying in length up to about '01 inch, and 

 exhibiting the two usual polarization-tints of the first order, the 

 yellow dominating. Parts of the slice, however, show an approach 

 to ' thorn-structure ' ; others streaky patches of flakes, arranged so 

 as to produce a nearly-uniform colour and simultaneous extinction. 

 Two grains, showing a cleavage like that of augite, but acting 

 feebly on polarized light, may represent remnants of that mineral. 



The last specimen, ' from the moraine of the Schwarzenberg 

 Glacier,' — a very typical one of the rather lighter-green hard 

 serpentine, though not very fissile in the hand-specimen, is shown 

 by the powdered magnetite to have been much crushed. It is 



1 The mountains from the Allalinhorn to the Egginerhorn are coloured as 

 serpentine in the Swiss Geological-Survey map, but Griiner Schiefer also 

 occurs in the range. [T. Gf. B.] 



2 The apparent dust, under a high power, often resolves itself into minute 

 clear films. 



3 Each of these statements may be made of a schistose serpentine (rather 

 richer in magnetite) but recently sliced. It was collected in 1889 from the 

 old moraine on the left bank of the Findelen Glacier, where it was rather 

 common. This leads me to suppose that it comes from the Gorner-Grat mass — 

 probably from somewhere near its north-eastern end. [T. G. B.] 



4 The confusion may be due to the accidental direction of the slice, which, 

 as the rock showed no very definite structure, was cut to suit convenience. 



