326 APPENDIX. 



1. It fuses easily before the blow-pipe into a spongy, sinning and 

 transparent glass ; with acids it forms a jelly. 

 2. Analysis. 



By MONTICELLI & COVELLI. By KOBELL. 



Silica . . 54-16 . . . 43-96 



Lime . . 31-67 . . . 31-96 



Magnesia . . 8-83 . . , 6-10 



Alumina . . 0-50 . . . 11-20 



Oxide of iron . . 2-00 . . . 232 



Soda . . 0-00 . . . 4-28 



Potash . . 0-00 . . . 0-38 



3. It occurs among the ejected minerals of Mount Vesuvius. 



HYDROBORACITE. HESS. (See Neues Jahrbuch fur 

 Min. Geog. Geol. u. Petre. von. LEONHARD u. BRONN, 

 1834. ' p. 353.) 



IRIDOSM1NE. (See Vol. I, p. 281.) 



M 



P on z 



1183 



Sp. gr. =19-38... 19 47. 



The crystals are shorter than in the annexed figure. Color tin white. 

 Hardness =7 0. Undergoes no change before the blow-pipe, and emits 

 no odor. They are found in the gold-sands of Newransk 95 wersts from 

 Catharineburg, and in many other places in the Ural. 



Crystals from Nischne Tagil have the same form, but a lead-grey col- 

 or and a Sp. gr. =21-118. Before the blow-pipe their surface becomes 

 dull, turns black and gives out the smell of osmium. 



