Professor T. O. Bonney — Rocks from Kimherleij. 451 



includes mineral and rock fragments, as usual, the largest (rock) 

 being rather more than o" in diameter. Among the former, except for 

 one small grain of brown mica, I can only identify with certainty 

 olivine, which shows varying amounts of serpentinization. The 

 matrix differs only in one respect from that last described, and from 

 its usual character in this rock — that it has a more pronounced brown 

 tint, due to the abundance of a rather minute mica, as described, 

 above, which sometimes appears almost to form a "setting" for the 

 other minerals. The second specimen, labelled " West Blue," departs 

 in two directions from the normal type : (a) the mineral fragments 

 almost all consist of a greenish-yellow serpentine ; (6) the matrix 

 generally exhibits a distinct warm-brown tint, due to the occurrence 

 of a mica in numerous small rectangular plates. This mica, with 

 a magnification of about 80 linear, is seen to be more definite and 

 regular in outline, richer in colour, and more abundant than in the 

 last-named or in any other specimen that I have examined. In 

 one or two places we find, associated with it sporadic clusters of 

 a small prismatic mineral, about '005" in length, which is practically 

 colourless, affords high polarization tints, and extinguishes at 

 angles ranging up to about 40°. This mineral, which I think we 

 may identify as an augite, is included in both the mica and the 

 serpentine. The latter mineral, in the matrix or in small enclosures, 

 sometimes exhibits a tendency to spherulitic structure. All, I think, 

 must be of secondary origin, and the aspect of the mica leads me 

 to suspect slight contact metamorphism, such as might be produced 

 by a dyke. 



We come next to the rock fragments. A few are holocrystalline ; 

 the rest are sedimentary.^ The former are represented in (a) by 

 the following : one which contains parts of two grains of olivine 

 (this, however, might possibly be a compound porphyritic crystal 

 rather than a bit of a peridotite) ; another which consists of two 

 flakes of brown mica, with an interstitial mineral, probably calcite ; 

 a third which is formed of a piece of a garnet, with a border of 

 kelephite (on the outer side only),^ and of a colourless augite. 

 This, no doubt, represents the rock containing red garnet and green 

 pyroxene^ which was described from larger fragments by Miss 

 Eaisin and myself.^ Among the fragments more or less certainl}'- 

 of sedimentary origin, the commonest type, subangular in shape, 

 consists of a compact, rather dark-purplish rock, with a pale greenish - 

 grey border, sometimes banded ; but the tints exhibit minor 

 variations, small fragments sometimes having their inner part of a 

 paler and redder colour with a more jaspery aspect. The microscopic 

 structure similarly varies. The outer zone commonly exhibits 

 a slight brownish tint, which darkens towards the inner side. With 

 a magnification of about 80 diameters, this is seen to be crowded 



^ For purpose of reference we may denote the specimen from the three places 

 mentioned above as a, b, c, respectively. 



^ This obviously must have been formed after the fragment was imbedded in 

 the breccia. 



^ The chrome diopside of Professor CarviU Lewis, op. cit., p. 21. 



« Geol. Mag. 1891, p. 412. 



