Til K CxlKNOHMlHTON METEORITE. 
71 
When the etching was carried out still further the damascene effect 
became lost, the Neumann lines were well developed and the surface of the 
kamacite crystals became rough owing to the greater resistance of small pin- 
point portions which do not appear to an equal extent in all the kamacite 
surfaces, but which seem to have an even and rather systematic network 
distribution throughout the whole mass. These more resistant pin-points may 
indicate the existence of minute segregations of carbon throughoutt he kamacite. 
The richer nickel-bearing material which has filled in the interstices 
between the kamacite crystals is very reminiscent of the form which quartz 
assumes in its intergrowth with felspar in graphic granite. These sharply angular 
and triangular masses have a distinctly yellowish reflecting surface compared 
with the kamacite, and not infrequently appear to have a marked border, 
rather thin but distinctly lamellar (see Plate VII, fig. 1). It may be that in 
these cases we may have an outer lamellar envelope of taenite wrapping up the 
plessite. 
The troilite granules are all small, averaging little more than 1 mm. in 
diameter, though some reach 2 mm. They are abundant and distributed some- 
what unevenly, occur indiscriminately in the kamacite, in the tsenite and 
plessite, and sometimes form a compound granule with what is believed to be 
schreibersite. 
This latter mineral occurs as irregular-shaped nodules, brittle in character, 
with a paler yellow reflecting surface than the troilite, with surfaces showing 
cleavage faces and much rougher than the nickel rich material filling the 
interstices, and offers considerable resistance to the attack of quite strong 
nitric acid. 
Separate chemical analysis has not been carried out on this material, 
but it is believed to be schreibersite (iron-nickel phosphide). 
The kamacite crystals are arranged, as one might expect in a brecciated 
octahedrite, with the Neumann lines of adjacent grains generally showing no 
relationship whatever to one another (Plate VII, fig. 2). 
When the etched surface as a whole is viewed by reflected light, great 
variation is noted between adjacent crystals or adjacent groups of crystals in 
their surface illumination according to the incidence of the light. This so-called 
“ schiller” effect of some writers on meteorites is very pronounced owing to the 
different orientation in different groups of plates, and is illustrated in the three 
figures of Plate VI, in which the same surface has been photographed with light 
coming from different directions. The curved line on the top surface of each 
figure marks the base of one of the cup-like depressions, and it is noteworthy 
that the fresh metallic material has only the thinnest oxidised coating. In the 
photographs on Plate VI the Neumann lines on the kamacite (k) plates are 
seen clearly. Schreibersite (s), taenite and plessite (t), and troilite (tr) may also 
be identified in the figures. 
