THE BOND SPRINGS STONY METEORITE 
55 
it forms fine intergrowths with kamacite; in some of these 
the mineral associated with the taenite etches more strongly 
than typical kamacite, and turns black (PL XIT, fig. 3), but 
this blackened material usually grades into typical kamacite 
away from the intergrowth. There is no evidence to prove 
whether the more intense etching is due to the small size of 
the kamacite grains in the intergrowth, or to the presence 
in them of some substance such as a phosphide in solid 
solution. Apart from such intergrowths, taenite associated 
with kamacite occurs either as relatively large inclusions with 
fine saw-tooth edges (PI. XII, fig. 1) or as thin films moulded 
on the margin of kamacite areas (PI. XII, fig. 2). 
Taenite is also intimately associated with p5au’hotite, often 
in subgraphic intergrowths over small areas (PI. XII, figs. 
5 and 6). Etching with picric acid and with bromine water 
shows that taenite is the only iron-nickel mineral in these 
intergrowths. 
Unidentified NicJiel-Iron Constituent. In addition to the 
two nickel-iron alloys just described, a third creamy-white 
opaque mineral occurs as irregular lamellae in the kamacite ; 
it can be discerned only liy etching with 2 per cent, picric 
acid in alcohol for about 30 seconds; see Plate XII, figs. 1, 
2 and 4; in fig. 4 etching is complete; in figs. 1 and 2, the 
mineral is present in the kamacite to the same extent as in 
fig. 4, but in fig. 1 etching has not been carried far enough to 
make it visible, while in fig. 2 it is just beginning to appear. 
Bromine water does not etch it, but nitric acid attacks both 
kamacite and the lamellar mineral. Standard etching re- 
agents produce similar results with the lamellar mineral and 
its kamacite host, so that the lamellar mineral is probably a 
nickel-iron alloy. Dunn (4, p. 269) notes similar lamellae 
in the Rangala Meteorite, and suggests that they may be due 
to twinning. 
The lamellae are formed from coalescence of lens-shaped 
( ?) ex-solution bodies, which, when they have failed to 
coalesce, occur in rows (PI. XII, fig. 4). The lamellae are 
sub-parallel and somewhat curved; where the kamacite area 
narrows to a “waist,” and then widens again, the lamellae 
tend to converge and to diverge correspondingly. Frequently 
a second, more weakly developed, series runs at right angles 
to the more prominent lamellae, and sometimes a third, still 
more weakly developed, series is inclined to the other two; 
presumably these lamellae lie in the more or less distorted 
cleavage directions of the kamacite host. It is highly probable 
