414 Prof. Bonney and Miss Raisin — Rocks from Kimherley. 



the serpentine in a sub-ophitic way. "Within the ground-mass are 

 well-formed crystals of green Augite, also red Garnet and brown 

 Mica. Some Olivine is in good preservation, and Serpentine occurs, 

 dark- to light-green, the result of the alteration of a ferro-magnesian 

 silicate, most probably an Olivine rather rich in iron. The rock 

 thus would seem to be a Granatiferous Picrite, 



YII. These irregularly cylindrical bodies consist apparently of 

 small fragments of the minerals of the rocks. Garnet, Pyroxene, etc., 

 and also of well-rounded Quartz grains, all the constituents being 

 cemented together, apparently by Calcite. The structures may very 

 possibly be concretionary and have formed within a sandy rock. 



VIII. From examination of the powder obtained by crushing a 

 fragment, this specimen appears to be Pyroxenic, — a pale-greenish 

 minutely crystalline Augite. 



IX. This rock consists of red Garnets, with rather perfect crystal 

 faces, imbedded in a brown ground-mass. A slide has been prepared 

 which shows that the matrix consists of an ill-defined crystalline 

 mass, including either incipient or partially-decomposed forms of 

 a mineral which has an appearance suggesting crystal outlines 

 of a Felspar-like character. Some Quartz may also be present. A 

 brown Mica occurs, rather iron-stained, and somewhat confusedly 

 crystallized. There are also crystals, which are short stout prisms, 

 rather rounded, terminating in basal and dome planes, transparent 

 and colourless, highly refractive, and with straight extinction ; these 

 may possibly be Topaz. The somewhat decomposed and iron- 

 stained condition of the rook makes it difficult to speak with 

 precision, but on the whole the probability is that it is a somewhat 

 altered fine-grained Granatiferous Mica-Diorite. 



X. Quartz pebbles. 



Note hy Prof. T. Bupert Jones, F.B.S. 

 The following specimens were previously supplied by Mr. L. 

 Atkinson, and returned to Kimberley labelled for the use of the 

 miners and others. 



1. Slag of "Blue Ground" (local matrix of the diamond) arti- 

 ficially burnt. 



2. Tufaceous concretions, roughly cylindrical and branched, 

 formed locally near the surface, from the decomposition of the 

 felspar of igneous rocks yielding carbonate of lime, and the calci- 

 ferous water percolating sandy strata. 



3. Pebbles and fragments of chalcedony from the agates of 

 amygdaloids, either local or drifted from the upper country. 4. 

 Quartz crystal, probably from an agate. 5. Calcite, probably from 

 the local tufa or from an agate. 6-10. Iron-pyrites in irregular, 

 knobbly, concretionary forms; Hematite; Ilmenite; Garnet; Epidote; 

 probably from the " Blue Ground." 



11. Sbale veined with calcic carbonate. From the "Kimberley 

 Shale " of the " Lower Karoo " formation, ti-aversed by the diamond- 

 stuff. 12. Porcellanite ; possibly burnt shale. 13. Silicified wood ; 

 coniferous, from the " Upper Karoo " formation. 14. Soft ferru- 



