[ 70 ] 



XII. Intelligence and Miscellaneous Articles. 



ISOPYllE, A NEW MINERAL SPECIES. 



THE following account of this mineral by W. Haidinger, Esq. 

 F.R.S. E. &c. as well as the four following notices, we copy 

 from the last number of Professor Jameson's Journal. 



1. Description.— Regular forms not observed. Very pure masses 

 of considerable size, often nearly two inches in every direction, oc- 

 cur imbedded in granite. 



Cleavage none. Fracture conchoidal ; highly perfect, where the 

 mineral is pure ; of lower degrees of perfection, where there are 

 foreign admixtures in it. 



Lustre vitreous, often considerable. Colour grayish-black and 

 velvet-black, occasionally dotted with red, as in the heliotrope. 

 Streak pale greenish-gray. 



Opake, or very faintly translucent on the thinnest edges, with a 

 dark liver-brown tint. 



Brittle. Slight action on the magnetic needle. 



Hardness =5'5. . .6*0. Specific gravity =2*912. 



2. Observations. — Several specimens of the species of isopyre are 

 preserved in the cabinet of Mr. Allan. Some of them are quite 

 pure, and have no rock attached to them ; others are imbedded in 

 a kind of granite, chiefly consisting of quartz, crystals of which 

 often penetrate the dark-coloured mass of the isopyre. Someof the 

 specimens were procured by Mr. Allan three years ago, on a journey 

 through Cornwall, in which I had the pleasure of accompanying 

 him, from a miner in St. Just; others were given to Mr. Allan by 

 Mr. Joseph Carne of Penzance, whose collection of minerals is par- 

 ticularly rich in the products of the western districts of Cornwall. 

 The west of Cornwall is certainly the native country of the isopyre, 

 but I am unable at present more accurately to indicate its locality, 

 as I then considered the substance actually to be, what it was called, 

 black opal, and, as such, much less interesting than it proved on 

 more attentive examination, and omitted to take a note of the ex- 

 act locality. 



The resemblance of the isopyre to obsidian, or to what might be 

 supposed to be the appearance of opal, when of a black colour, is 

 very ^considerable; only the lustre of isopyre is less bright and 

 glassy than that of obsidian. It is also very much like certain va- 

 rieties of iron slag, and in fact it would be difficult to suspect the 

 mineral not to be a product of the same kind of fusion which we are 

 capable of producing in our own furnaces, if it were not associated 

 with crystals of quartz, or did not contain, as in one of Mr. Allan's 

 specimens, small imbedded crystals of tin-ore and of tourmaline. 

 In allusion to this appearance, and also on account of the perfect 

 similarity of a globule melted before the blowpipe, with the frag- 

 ment employed in the experiment, I propose the trivial name of 

 Isopyre, for designating the mineral, from wo; (equal) and iru§ (fire). 

 The similarity of properties is even preserved in regard to mag- 

 netism, 



