ORDER I. RIIOMBOHEDRAL AL0M-HALOIDE. 67 



a candle. Before the blowpipe it is first perfectly liquefied, 

 but soon becomes hard again, and assumes at last a slaggy 

 appearance. It is insoluble in water, though it appears in 

 it of a higher degree of transparency, and, according to 

 Mr ALLAN, more easily admits of cleavage, after having 

 been kept in it for some time. 



2. It occurs in Arksut-fiord, West Greenland, in two 

 small layers in gneiss, one of which contains only the 

 white varieties, whereas the other contains the coloured 

 ones accompanied by hexahedral Lead-glance, several spe- 

 cies of Pyrites, rhombohedral Quartz, and imbedded crys- 

 tals of brachytypous Parachrose-baryte, and prismatic 

 Feld-spar. 



GFKCS III. ALUiM-HALOIDE. 

 1. RHOMBOHEDRAL ALUM-HALOIDE. 



Rhomboidal Alumstone. JAM. Syst. Vol. II. p. 599. 

 Man. p. 29. Alum-stone. PHILL. p. 196. Alaun- 

 stein. WERN. Hoffm. H. B. II. 2. S. 78. Alaunstein. 

 HAUSM. II. S. 465. Alaunstein. LEONH. S. 623. 

 Lave alte'ree alunifere. HACY. Traite, T. IV. p. 504. 

 Alumine sous-sulfatee alcaline. Traite', 2de Ed. T. II. 

 p. 128. 

 COHDIER. Ann. de Chim. Vol. IX. p. 71- 



Fundamental form. Rhombohedron. R = 92 5CK. 

 Vol. I. Fig. 7. PHILLIPS. 



a = V 3-892. 



Simple forms. R oo (6) ; R (R). Char, of 

 Comb. Rhombohedral. Combination. 1. R oo. 

 R. Fig. 111. 



Cleavage. R oo rather perfect. Traces of R. 

 Surface, smooth and even. The faces of R 

 sometimes streaked parallel to their edges of com- 

 bination with R GD. 



Lustre vitreous, inclining to pearly upon the more 



