The, Meteoric. Irons from Griq^iialand East, South Africa. 15 



The sp, gr. was determined by Dr. W. Leick as 7'7876 (temp. 

 14|-° C), the weight of the piece being 162-954 grams. From this, 

 and taking the accessory constituents into consideration, the sp. gr. 

 of the nickel-iron is 7-8137.* 



B. — The Iron from Matatiela in the South African Museum. 



For investigation of the South African Museum specimen I had 

 at my disposal eight slices, weighing in all 388 grams and having a 

 total cut surface of 153 sq. cm. 



The beams here reach 4 cm. in length, are only slightly rounded at 

 the ends, and show Neumann lines f very distinctly (" schraf&rter 

 Kamazit "), as w^ell as etching-hollows in varying numbers. On 

 slight etching the lines often appear alone, on stronger etching the 

 hollows become more numerous and may finally, to some extent, 

 conceal the lines. Frequently several beams lie close together ; they 

 rarely touch directly, being more usually separated by much elon- 

 gated particles of plessite, which are often so narrow as to be easily 

 overlooked. The beams are distinguished by a marked orientated 

 sheen which is common, sometimes to alternate beams, sometimes to 

 each of a continuous group of these. 



Taenite is poorly developed and is recognisable with certainty only 

 after somewhat strong etching. The fields are numerous, attaining a 

 maximum area of 0'5 sq. cm. and showing great variation in dimen- 

 sions, form, and structure. The smaller are frequently narrow, 

 elongated, and very dark, the larger are fairly isometric and of a 

 light grey colour. " Combs" proper, that is, continuous growth of 

 the taenite surrounding the beams, are rare, and are limited chiefly 

 to narrow marginal areas. On the other hand, many of the larger 

 fields are regularly interstrewn with slightly bent, strongly lustrous 

 taenite-like scales of about 0-01 mm. in thickness. These scales 

 attain a maximum length of about 0-04 mm., but are usually much 

 shorter; they are arranged parallel to the octahedral planes and 

 follow one another at intervals of from 0-02 mm. to 0-2 mm. Possibly 

 we have here net-shaped, perforated, larger lamellae of taenite with 

 the meshes filled in with kamacite. The lighter or darker colour of 

 the plessite appears entirely, or almost entirely, dependent on the 

 number of the above-mentioned scales. Some of these fields are 



* The following specific gravities were taken as bases for calculation : Iron- 

 nickel-phosphide 7-1118, Troilite 4-75, Ferrous chloride 2-528 (after Filhol). 



t The etched surface reproduced in Plate V., Pig. 2 is intended to show the 

 general and not the minute structure, and it shows the Neumann lines distinctly 

 in the bars towards the left edge only. 



