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III.—On some Rock-Specimens from Kimberley, South Africa
Published online by Cambridge University Press: 01 May 2009
Extract
A Paper on the diamantiferous rock of Kimberley by Sir J. B. Stone, M.P., Miss Raisin, and myself, was published in this MAGAZINE in 1895. Since then the first-named has received from friends in South Africa another parcel of specimens, obtained, at a greater depth than heretofore, in the De Beers mine. These specimens, twenty in number, he kindly entrusted to me for description.
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- Copyright © Cambridge University Press 1897
References
page 448 note 1 Geological Magazine, 1895, pp. 492, 496.Google Scholar
page 448 note 2 Reference to these is made in “The Genesis and Matrix of the Diamond,” by the late ProfessorLewis, H. Carvill, p. 69.Google Scholar
page 448 note 3 “Papers and Notes on the Genesis and Matrix of the Diamond,” 1897 (Longmans).
page 448 note 4 I mention the size here and elsewhere in order to show that my conclusion as to the origin of the rock is not founded on small specimens, which in the case of so variable a rock as the breccia is of some importance.
page 449 note 1 The specific gravities were determined by a Walker's balance. In this and several other matters I have to thank Miss C. A. Raisin, B.Sc, for kind help.
page 450 note 1 For the structures of the serpentine and the olivine, see Lewis, ut supra, p. 14.
page 450 note 2 In our former paper we separated the dark-coloured varieties as possibly pseudobrookite, because we thought sundry slight differences, not only dependent on size, were perceptible. But study of these slices and of Professor Lewis's description makes me doubt whether the latter specimens are more than impure perofskite, so I follow him in placing all under the one name.
page 450 note 3 A true white mica may be present among them, but in most cases a faint yellowish tint with a trace of pleochroism is perceptible. I think this mineral must be authigenous.
page 451 note 1 For purpose of reference we may denote the specimen from the three places mentioned above as a, b, c, respectively.
page 451 note 2 This obviously must have been formed after the fragment was imbedded in the breccia.
page 451 note 3 The chrome diopside of ProfessorLewis, Carvill, op. cit., p. 21.Google Scholar
page 451 note 4 Geol. Mag. 1891, p. 412.Google Scholar
page 452 note 1 Minute perofskite may be present in this fragment.
page 453 note 1 I now think it more likely than when I wrote the preface to Professor Lewis' papers, that this has given a serpentinous aspect to certain small fragments which I then conceived might represent a compact or glassy peridotite.
page 453 note 2 The pieces left are still too hard to crush between finger and thumb. This seems to indicate that calcite or dolomite is not the only cement of the rock.