408 DETERMINATION OF MINERALS. 



ALBITE, p. 277, OLIGOOLASE, p. 276. H.=6; G.-256-272; 



triclinic, but cryst. as in ortlioclase, except that the two cleavage 

 planes niake an angle of 93i c to 94", and one of them has the surface 

 striated ; white usually, flesh-red, bluish ; B.B. fuse with a little 

 difficulty ; not acted on by acids. 



LABRADORITE, p. 276. H. =6 ; G.=2'66-2-76 ; triclinic, like albite 

 in cryst., and nearly in cleavage angle, 93° 20', and in striae of 

 surface ; white, flesh-red, bnh red, dark gray, gyh brown ; B.B. 

 fuses easily ; decomposed by HC1 with difficulty. 



ANORTHITE, p. 275. H .=6-7 ; G. =2 -66-2 -78 ; cryst. and striae 

 as in albite, cleavage angle 94° 10' ; white, gyh, rdh ; B.B. fusion 

 difficult ; decomposed by HC1 with separation of gelat. silica. 



MICRO CLINE, p. 278. Very near orthoclase in all characters, but 

 triclinic, cleavage angle differing only 16' from a right angle, and 

 surface of most perfect cleavage stiiated, but striee exceedingly 

 fine, often difficult to detect with a good pocket lens, and requiring 

 the aid of a polariscope ; color white, gray, flesh-red, often green. 

 For optical distinctions of Feldspars, see p. 274. 



EUCLASE, p. 288. H.=75; G.=31 ; in monoclinic crystals, with 

 one perfect diagonal cleavage ; pale green to white, bnh ; trans- 

 parent ; becomes electric by friction. 



