B22 yfccojwt ajul Description of a Stone 



** The second substance is lamcllated pyrites (sulphuret 

 of iron) of a white colour inclining a little to that of nickel: 

 it is sometimes dispersed througliout tlie mass in grains, and 

 ftometimes it lines the fissuvts interspersed in the stenc. 

 This pyrites experiences only a very slight, partial, and tran- 

 sient eftcrvescencc in acids : it is not susceptible of attrac- 

 tion bv the magnet ; by the blowpipe it readily gives a frit 

 interspersed with small globules like other pyrites. That 

 in a thin stratum on the sides of the fissures has a gray and 

 less brilliant colour. It ccmtains less sulphur, and ap- 

 proaches near to malleable iron in grains. 



" The third, which is very rare, is under the form of 

 spherical or irregular globules of a dark gray colour, brittle, 

 jmd having a smooth compact fracture. It produces no ef- 

 fervescence in acids ; is not susceptible of attraction by the 

 mauiiet ; is refractory to the blowpipe, and assumes in it 

 onlv a red and black tint. When scratched with a graver 

 this substance assumes a metallic colour like trap. 



" Besides the gray globules I found also other globular 

 and irregular bodies of an olive-green ground inclining 

 sometimes to yellow, the fracture of which has a fat shining- 

 aspect like the steatites of Briancon, and which are not verv 

 hard. As several of these bodies lose their distinguishing 

 character, approaching more or less to the appearance of 

 paste; and besides, as they are in very small quantity, I did 

 not think it proper to include them among the number of 

 the contained substances. 



" 'I'he surface of this stone is a vitrified black crust, 

 sliffhtly puft'cd up, which strikes lire with steel ; of a quarter 

 of a line in tliickness at most, and in the surface of which 

 are observed a few grains of iron and some gray globules, 

 which being more refractory than the rest of the paste have 

 resisted the effects of the heat. 



*' It is to the^e grains and these globules, which in all 

 probabilitv have been detached from the mass by the fusion 

 of the neighbouring parts or by the intensity of the heat, 

 that we ought to ascribe those blue sparks which escaped 

 from the mass during its course. 



" It is also to be remarked, that in a fragment of this 

 stone the vitrification has been efteeted in a part of an in- 

 terior fissure lined with pyrites, with this diffeience, that 

 this vitrification is much more puffed up. 



" The interior of the stone even in the parts nearest to 



the vitrified crust does not seem to have undergone any 



change by the action of the fire, only its granulated tissue has 



that lax aspect observed iu all stones which with this kind of 



S aggregation 



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