L L.2 Prof. Maskelyne and Dr. Lang's Miner alogical Notes. 



Pcnington, and presented to the Hon. East India Company, 

 who have deposited it in their museum." 



With the exception of a small portion broken off at what may 

 be termed the apex of the aerolite, the entire stone was sent to 

 Europe. Its form is rudely pyramidal, of which the edges, 

 especially where they culminate at the broken apex, are rounded 

 so as to give a convex character to that part of the mass. Ridges 

 and valley-like depressions converge towards the apex, which, 

 while they grow deeper and more marked the further they recede 

 from it, become mere linear markings or cracks in the crust 

 where they traverse the convex surfaces that would culminate 

 on the summit. On the base of the aerolite, on the underside, 

 namely opposite to the apex, the crust is accumulated in pitch- 

 like prominences ; in other parts it presents a smooth dull aspect, 

 and has a dark rich brown colour. It exhibits fissures and lines, 

 resulting no doubt from contraction as it cooled. It has also 

 small shining dark points which correspond apparently with 

 spherules. 



The structure of the Durala stone is that of a rather loosely 

 aggregated chondritic aerolite. The ground-mass is of a pale 

 grey hue, exhibiting a whitish granular mineral interspersed 

 among waxy nodules. Like Nellore, it does not take a polish. 

 It differs from Nellore in the distribution of the iron, which is 

 scattered in somewhat larger particles, and less evenly than in 

 that aerolite. Some of the iron granules are as much as ygth 

 of an inch in diameter. On the other hand, in no aerolite 

 that I have seen is this metal diffused in a more minute form of 

 dust than in Durala. The ground-mass exhibits under the 

 microscope a larger amount of the granular mineral than Nel- 

 lore ; and spherules and nodules, some smooth, some angular in 

 outline, are distributed through this mass, and most frequently 

 present under the microscope the usual characteristics of the 

 waxy (probably olivine) spherule. Occasionally, too, we see a 

 barred structure sometimes fanned out and radiated, or a mine- 

 ral with a mottled aspect and without much colour in polar- 

 ized light, or very definite planes of polarization. Other sphe- 

 rules, again, exhibit a number of crystals within them enclosed 

 in a mass with sometimes a hexagonal outline, but not with an 

 orientation exhibiting any evident morphological relation to that 

 outline. 



The individual minerals are very much like those in Nellore ; 

 and a very few crystals of a felspar-like mineral may be also 

 detected in Durala. 



The cut face has two metallic veins running across it. Its 

 specific gravity = 353. 



