EUCHROITE. 95 



a : b : C = 1 : *J 0-923 : J 0'3-U. 



Simple forms. P oo (P) ; P -f o> (M) = 1 17 

 (X ; (Pr -h QD) 5 () =.95 Iff ; (Pr + oo) 3 (i) 

 = 78 47' ; fr (w) = 87 52' ; f r + OD (&). 



Combinations. 1. P oo. Pr. P -f QD. (Pr-f- oo) 5 . 

 oo. f r. P+ co. (Pr+ oo) 5 . (Pr + oo) 5 . 

 oo. Fig. 192. 



Cleavage, indistinct, parallel to n and m, interrupt- 

 ed. Fracture small conchoidal, uneven. Sur- 

 face the vertical prisms striated, parallel to their 

 common edges of combination, P oo often 

 rounded. 



Lustre vitreous. Colour bright, emerald-green. 

 Streak pale apple-green. Double refraction con- 

 siderable. Transparent, translucent. 



Rather brittle. Hardness = 3-5 ... 4-0. Sp. Gr.- 

 = 3-389. 



According to, Dr TURNER, it consists of 



Peroxide of Copper 47*85. 



Arsenic Acid 33-02. 



Water 18-80. 



In the matrass it loses its water, and becomes yellowish- 

 green and friable. When heated to a certain point upon 

 charcoal, it is reduced in an instant with a kind of deflagra- 

 tion, leaving a globule of malleable copper, with white 

 metallic particles dispersed throughout it, which are entirely 

 volatile at a continued blast 



It was discovered at Libethen in Hungary, in quartzose 

 mica slate, and brought to London, under the name of 

 Euchroite. It will enter the genus Emerald-malachite of 

 MOHS, under the name of the prismatic Emerald-malachite. 



