I'n-f. T. <; Unimex (> ]: d a ml ntti> ,!;> .< metu 



Another specimen has now been found. Tin- pyrope apparently was 

 rounded in form. about a ] inch in diameter, and surrounded by a 

 kelvphite rim. It is broken across, thus di-ii-lo-ing the diamond, an 

 octahedron, only one face of whirh i- completely expi-ed. This is 

 slightly stepped, and measures roughly one-tenth of an inch along the 

 t-d-c. A small piece of the usual purplish breccia adheres to the 

 pyrope. so the case i- exactly parallel to the former one. In each the 

 perfect form of the diamond shows that it crystallised liefore the 

 garnet, and as the ordinary varieties of the latter mineral seem to l>e 

 produced at a high temperature.* the association may IKJ significant. 



(3.) Tin ('{,,, //,*/.. 



A fe\\ s]>ecimens of this were also sent, l>ut only two varieties pre 

 sent any feature of interest. One is a greenish conglomerate with 

 calcareous matrix, and rounded pebbles up to aloui \ inch diameter : 

 the other has a jwde-grey matrix, speckled with .some small angular 

 dark-green fragments and a few sub-angular pebhles up to about an 

 inch in diameter ; one apj>arently a red felsite, the others diabase. In 

 the first specimen the microscope shows abundant sub-angular to 

 rounded grains, mostly diabase, of which there are at least half a doy.en 

 varieties, a microgranite and two or three rocks more fragmental in 

 aspect ; one perhaps a tuff, another apparently a quart/he, affected 

 by pressure, and a third a suit-crystalline dolomite. These are cemented 

 by microgranular calcite, containing probably a little magnesia (the 

 crystals often forming a kind of border to the rock fragments), the 

 interspaces being filled in with clear dolomite. In this cement are 

 embedded some angular bits of quart/, a fragment of altered felspar, 

 and one or two, perhaps, chalcedony. The other specimen shows a 

 fine-grained muddy matrix, in which are scattered angular to siuV 

 angular grains of quartz, with a little decomposed felspar, a little of a 

 green mineral (1 replacing pyroxene), decomposed iron oxide, and 

 perhaps some small rutiles, with rock fragments, generally rather 

 rounded, representing compact diabase, or possibly sometimes andesite, 

 and one or two of a sulHcrystalline limestone. Both these specimens, 

 as Mr. Tnibenbach informs me, represent a rock named "bastard 

 blue" by the miners, and it has l?en pierced in both shafts, the 

 diamautiferous breccia, or " blue ground," apparently pissing under it 

 in the second shaft. As, however, their is no real relationship between 

 the two rocks, I regard the association as fortuitous. 



* I do not forget the remarkable gurnets from the Ba*togiie, described by Pro- 

 fe?or Renord (' Bull, du Musee Royal d<- Belgique,' vol. 1, p. 9), or that called 

 jirreueite (also one of the andradite group), but both these minerals are very 

 abnormal. [The pene.*i* of the former is disK-usscd by Miss C. A. Raisin, D.Sc., in 

 n paper which will appear in the ' Quarter!} Journal of the Geological Society' 

 "l.j 



