PHYSIOGRAPHY. 



Botryogene Bournonite. 



83 



Hardness =2-0 . . . 2-5. Sp. gr. =2-039. 



Compound Varieties. Reniform and botryoidal shapes; 

 the individuals are often regularly terminated at the surface 

 of these shapes. Color ochre-yellow. 



1. Before the blow-pipe, in a glass tube, it intumesces, and gives off 

 water, leaving a reddish yellow earth behind. It is very slowly soluble 

 in water, to which it imparts a much more feebly astringent taste than 

 sulphate of iron. 



2. Analysis. 

 By BERZELIUS, 



Sulphate of iron . . . 48-3 



Sulphate of magnesia . . . 20-8 

 Water . . . 309 



8. It is found coating Gypsum and Iron Pyrites, associated with Epsom 

 salt and Copperas in the great copper mine at Fahlun. 



BOTRYOLITE. (See Datholite.) 



BOURNONITE. Diprismatic Copper-Glance. 



MOHS. 



Primary form. Right rectangular prism. 

 Secondary forms. 



Fig. 73. 



M 



P on d 93 40' 



P on o 87 8 



Cleavage distinct parallel with M and T, and with both 

 diagonals of the prism. Fracture conchoidal, uneven. 



