28 



Annals of the South African Museum. 



In three places at least I noticed the presence of platy inclusions, 

 0-1 mm. wide, which have a bluish-black colour and a strong 

 metallic lustre by reflected light. There is no doubt that these are 

 daubr^elite. The plates have irregular boundaries, and are orien- 

 tated obliquely to the longest diameter of the troilite. Schreibersite 

 occurs as tiny spangles or little zigzag rods, lying as a rule 

 wedged in between the bars, and in one place it forms a plate- 

 like piece, 7 mm. long. This is perhaps one of the so-called 

 Eeichenbach lamellse ; that is to say, it lies possibly parallel to a 

 cube face. 



The small amount of phosphorus in both analyses made, 0'06 

 per cent., shows that the schreibersite is really only sparingly pre- 

 sent, not that it is merely very indistinct. The accessory constituents 

 are found only in the portions showing numerous lamellae. They 

 are the first to crystallise out, and are followed by the lamellss, which 

 group themselves around them. The plessite forms last, and it 

 therefore appears to me that the absence of troilite and schreibersite 

 in those portions that are not lamellar, indicates that they are com- 

 posed of plessite. 



In order to ascertain if the small glistening scales which lie in 

 these non-lamellar portions are to be regarded as taenite, I had two 

 analyses made by Dr. Fahrenhorst. 



Table I, gives the composition of one piece, which showed the 

 structure characteristic of a finely lamellar octahedral iron ; Table 

 II. that of a piece without lamellas. As these showed no essential 

 differences, the sparingly occurring accessory constituents were 

 determined only once. Neither piece left any residue in aqua regia. 



