260 



PHYSIOGRAPHY. 



Hopeite. 



Color black. Streak greenish-grey. 

 Sectile. Soft. Sp. gr. = 3-045, 



1. If gently heated before the blow-pipe, it becomes magnetic ; in a 

 stronger heat, it melts into a dull, opake, black globule, and yields a yel- 

 lowish green glass with borax. 



2. Analysis. 



By BERZELIUS. 



Oxide of iron . . . 51-50 



Silica . . . 27-50 



Alumina . . . 5-50 



Oxide of manganese ... 0-77 



Volatile matter . . . 11-75 



Magnesia . a trace. 



3.. It has been found in the parish of Sva"rta in Sttdermanland, inter- 

 mixed with limestone. 



4. It is probable that it belongs to the species Limonite. 



HOPEITE. 



Primary form. Right rhombic prism. M on M'^- 



24'. 



Secondary form. 

 s on s over I 

 M on M over g - 

 P on P over M - 

 P on P' 



81 34' 

 101 24 

 139 41 

 107 2 



Cleavage parallel with the longer diagonal perfect, that 

 parallel with the base less distinct. Surface, plane I streak- 

 ed lengthwise ; the rest of the faces smooth. 



Lustre vitreous, pearly upon I. Color greyish white. 

 Streak white. Transparent . . . translucent. Refraction 

 double. 



