ORDER IV. PRISMATIC LIEOCOKE-MALACHITE. 161 



Fundamental form. Scalene four-sided pyramid. 

 P = 129 25', 85 11', 116 W. Vol. I. Fig. 9. 

 AP. 



a : b : c = 1 : V ' 5085 : V 1 ' 51 - 



Simple forms. Pr (o) = 71 59' ; P + oo (d) = 

 119 45'. 



Char, of Comb. Prismatic. 



Combination. 1. Pr. P + oo. Fig. 1. 



Cleavage, Pr and P -}- x imperfect, the first rather 

 more distinct. Fracture imperfect conchoidal, 

 uneven. Surface of both forms faintly streaked 

 parallel to their edges of combination. 



Lustre vitreous, inclining to resinous. Colour sky- 

 blue ... verdigris-green. Streak corresponding 

 to the colour, very pale. Semi-transparent ... 

 translucent. 



Nearly sectile. Hardness = 2-0... 2-5. Sp. Gr. 



Compound Varieties. Massive : composition 

 granular, sometimes very distinct, but altogether 

 rare. 



OBSERVATIONS. 



1. According to CHENEVIX, the prismatic Lirocone- 

 malachite consists of 



Oxide of Copper 49-00. 

 Arsenic Acid 14-00. 

 Water 35-00. 



Before the blowpipe it loses both colour and transparency, 

 emits fumes of arsenic, and is changed into a friable scoria, 

 containing some white metallic globules. With borax it 

 voi. TI. i, 



