452 Examination of the New Mineral Haughtonite. [No. 6. 



Examination of the New Mineral Haughtonite {a compound of 

 Carbonate of Lead and Sulphate of Barytes). — By Henry Pid- 

 dington, Esq. Curator, Museum of Economic Geology. 



Amongst a few common rocks and minerals presented by Lieut. 

 Haughton, Assist, to the G. G. Agent N. W. Frontier, on his departure 

 for the Cape, I found a coarse, dirty-white, earthy looking mineral, 

 which, judging only from its weight, might be taken for either an ore of 

 lead or one of barytes, but on examination it proves to be a compound 

 of both which I nowhere find described, and I thus deem it due to 

 Lieut. Haughton to put upon record my examination of it, in hopes 

 that we may in future obtain more and better specimens so as to enable 

 us to pronounce more positively upon it than we can now do. 



Our specimen is apparently the remains of an oblique rhomboidal 

 table, much broken down by exposure to the atmosphere or to the 

 action of water, and decomposing externally. 



Its external colour, feel, soiling, and hardness when scraped, are 

 exactly those of an impure earthy chalk ; but in our specimen there are 

 set numerous minute nodules (not exceeding a hemp seed in size) of a 

 harder kind of the same mineral, and when a surface is scraped these 

 shew a dull clayey shade, as if they were nodules of hard clay, though 

 they are not so. 



Its fracture, seen on a very small surface, is coarse hackly, and it is 

 of some considerable toughness. It shews also in the fracture thin 

 brown coloured veins, such as are sometimes seen in common earthy 

 iron ores from vegetable matter. 



It is externally very friable and soiling* It adheres a little to the 

 tongue and feels heavy. The internal colour is that of a dull dirty 

 fawn-coloured claystone, the lustre earthy, but perhaps in a strong light 

 a little saccharine. 



The smell is very remarkable, being oily and rancid, as if oil had 

 been spilled upon it, and this especially when it is pulverised or heated 

 high enough to drive off the water. 



The powder is of a dull, yellowish-white colour. The external 

 chalky surface then, is that of the decomposed mineral, which in some 

 parts is 0. 2 or 0. 3 of an inch in depth. Its specific Gravity is but 



