Examination qf Hyalmiderite, a new Mineral. 189 



§ 14s 

 A third slag, which had been found many years ao-o at 

 Lautenthal in the Hartz at copper- works where copper 

 pyrites was smelted, and the crystallization of which has been 

 described above (§ 8), I likewise obtained through the kind- 

 ness of M. Hausmann. Its specific gravity at the temperature 

 of 65-3 F. was 3-870. 



As I had convinced myself by a previous analysis, that it 

 contained copper, I directed through the solution in muriatic 

 acid, after the silica had been separated from it, a current of 

 sulphuretted hydrogen gas, treated the precipitate thus ob- 

 tained with nitric acid, and then separated the oxide of cop- 

 per by caustic potassa. The fluid remaining after the separa- 

 tion of the copper, was treated, whilst warm, with nitric acid, 

 and heated for some time, so as to bring the iron to the maxi- 

 mum of oxidation ; the analysis was then proceeded with as 

 usual. 



This slag from Lautenthal contained 



Silica 29-245 



Protoxide of iron . . 63-316 

 Peroxide of copper . 2*646 

 Magnesia .... ] -304 



Alumina 1-244 



Oxide of manganese . 1 -460 

 Potassa 0*184 



99-399 

 I consider that mineral as a slag likewise which Karsten 

 has described, and which Klaproth analysed, under the name 

 ot volcanic iron-glass*. According to Klaproth's analysis, 

 100 parts of it consist of 



Silica 29-50 



Protoxide of iron . . 66-00 



Alumina 4-00 



Potassa 0-25 



99-75 

 § 16. 

 The crystallized slag is consequently a silicate of iron. This 

 in the hyalosiderite appears to be combined with magnesia, 

 which seems to replace the quantity of iron in the slag. 



* Bcitrdge X.222 ff. Stromeyer in the Gott eel. Am. 1810 st. 194. 

 p ; ," , **. Hausmann has given further particulars of it in V. Moll's 

 ■hihrh. t |. B. u. II. III. 1815. p. •}!>. ffi 



From 



