370 Notice of Tremenheerite, a new carbonaceous mineral. [April, 



It is, when fresh, in masses of a scaly structure and of a deep black 

 colour, with a highly metallic lustre, much resembling coarsely foliated 

 graphite ; after a few months it partly falls to powder, or rather into 

 scaly flakes, evidently from the decomposition of pyrites, of which it 

 contains about three per cent. It powders easily, but the powder is 

 always scaly, soiling, greasy, and glittering, like graphite. If the pul- 

 verised part be washed and ground, the tougher metallic looking scales 

 remain as a black micaceous residuum, and it is only after long rubbing 

 and washing that they also are pulverised, showing great toughness in 

 the compacter and larger scales of the mineral. It soils much but is 

 too soft to mark with, nor can any very determined streak be made ; 

 what is so is of a deep black. When heated a little sulphur sublimes ; 

 the mass burns but very slowly indeed, reddening only at first and for 

 a long time like some varieties of graphite, and requiring a good supply 

 of air to the crucible and constant stirring to effect its combustion. 



With patient attention the whole is burnt, with the exception of a 

 small residuum of a very light, and bright fawn-coloured powder, which 

 is a mixture of oxide of iron and silex. 



Its composition is found to be in 100 parts, 



Carbon, 85.70 



Water and Sulphur, 4.00 



Peroxide Iron, 2.50 



Earth, chiefly Silica, 7.50 



99.70 

 Water and loss, , 30 



100.00 

 This mineral then differs from the anthracites in its high lustre, scaly 

 structure, and ready pulverisation, by which it approaches the gra- 

 phites ; as well as by its iron and very slow combustion ; but then from 

 these it differs by its streak, and high combustibility with nitre ; for, 

 like coal and the anthracites, when projected upon melted nitre it defla- 

 grates, heating the crucible instantly to redness, while the graphites 

 not only boil but heat the crucible also, and seem but partly and very 

 slowly to part with their carbon till a much higher heat is given. 



This distinction I have not yet found noticed in any chemical or 

 mineralogical work, but it seems to me to be no bad test by which to 



