160 PHYSIOGRAPHY. CLASS II. 



5. Where it occurs in sufficient quantity, it is used for 

 extracting copper. 



6. The only author who quotes crystals of the present 

 species is the Abbe' HAUY (Traite, 2de Ed. T. III. p. 471., 

 and Traite de Cryst. T. II. p. 577.). Crystals of this spe- 

 cies in fact may occur ; yet those which he describes cer- 

 tainly cannot be varieties of it, if they possess a specific 

 gravity = 2 '733. The forms are described as being pris- 

 matic, in which the ratio of the lines a : b : c is = 1 : 2 

 : A/ 2-5, the observed simple forms, P cc (P) ; P + co 

 (M) = 103 20'; Pr (1) = 120 52'; Pr (rf) = 115 22' ; 

 Pr + os (/), and the combinations: 1. Pr. P + os. Sim. 

 Fig. 2. ; 2. P _ cc. P + co. Pr + cc ; 3. Pr. P + co. 

 Pr + co. Sim. Fig. 9. Cleavage is said to take place pa- 

 rallel to P + co. The crystals are from Catharinenburg in 

 Siberia, and Very rare. 



The natural-historical determination of a species, besides 

 a knowledge of its forms, requires also the accurate investi- 

 gation of hardness and specific gravity. The latter does 

 not agree with that of uncleavable Staphy line-malachite ; 

 the former has been passed over in silence. Much is 

 therefore still wanting for a complete determination of 

 the species to which the crystals belong, which have been 

 described. 



GENUS II. LIROCONE*-MALACHITE. 

 1. PRISMATIC LIROCONE-MALACHITE. 



Di-prismatic Olivenite or Lenticular Copper. JAM. Syst. 

 Vol. II. p. 333. Prismatic Liriconite. Man. p. 94. 

 Octahedral Arseniate of Copper. PHILL. p. 316. Lin- 

 senerz. WERN. Hoffin. H. B. III. 2. S. 165. Linsen- 

 kupfer. HAUSM. III. S. 1051. Linsenerz. LEONH. S. 

 282. Cuivre arse'niate' primitif. HAUY. Tabl. comp. p. 

 90. Cuivre arse'niate octaedre obtus. "Traite', 2de 

 Ed. T. III. p. 509. 



From x<io s pale, and xovix dust or powder. 



