100 Canadian Record of Science. 



inch from tlie edge of the cross fracture. On the latter 

 surface, nearly an incli below the last named, three small 

 diamonds appear to lie in a line touching one anothei', 

 and near them are two others/ all four within a space 

 about three-quarters of an inch square ; an eighth diamond 

 is about an inch and a half away (on the same face) ; a 

 ninth, about one-fifth of an inch from the top edge ; and 

 a tenth occurs on the larger cross-fractured surface, but 

 near to the edge of the other one. These diamonds are 

 octahedra in form, generally with stepped faces— one, 

 at least, apparently twinned — perfectly colourless, with 

 brilliant lustre : the largest being quite 0.15 inch from 

 apex to apex, the smallest not exceeding 0.05 inch. AIL 

 seem to be embedded in the green part of the rock. As 

 the outer part of the boulder looks rather more decom- 

 posed than the inner, I had a piece removed from one 

 end, thus enabling me to study the mass to a depth of 

 more than an inch from the surface, and examined a stripy 

 about 4 inches long, in a series of five slices. 



The late Professor Lewis has given, in the volume 

 already mentioned, so full an account of the minerals 

 which occur in the " blue ground," that it will be needless 

 on the present occasion to do more than refer to his 

 descriptions,^ only calling attention to any variations iu 

 the mineral constituents and their ' association in these 

 eclogites. These constituents are : — 



1. {a) Garnet (Pyrope.)-— In the slice these appear a 

 light tawny or yellowish red tint, retaining this tint 

 (though much lighter) under the mioroscope.^ They are 

 generally clear, with frequent and irregular cracks, but 

 are occasionally traversed by wavy bands of minute en- 



1 It is jiossible that these two foriii a twill crystal, but I think they are separate. 

 As the point is uniniportant. I have not attempted to clear away the matrix. 



2 We must also not foi'get the paper by Professor Maskelyiie and Dr. Flight (Quart. 

 Journ. Geol. Soc, vol. xxx., p. 406), in wliich several of these minerals are described, 

 analysed, and identified. In fact, the authors ascertained everything that was possible 

 with the mateiials then obtainable. 



■! Unless it is expressly stated, the use of a l-iuch objective may be assumed. 



