COMPOUNDS OF ALUMINUM. 199 



alum is dissolved out. On evaporation the alum crystallizes 

 from the fluid in cubic crystals. This is called Eoman alum, 

 and is highly valued by dyers, because, although the crystals 

 are colored red by iron oxide, no iron is chemically com- 

 bined with the salt as is usual in common alum. 



Aluminite (Websterite). Another hydrous aluminum sulphate, in 

 compact reniform masses, and tasteless. From New Haven, in Sussex ; 

 Epernay, in France ; and Halle, in Prussia. 



LcBicigite is a potassium-aluminum sulphate, containing half the 

 water of potash alum. 



Amblygonite. — Lithium- Aluminum Phosphate. 



Triclinic, with cleavages unequal in two directions, mak- 

 ing an angle with one another of 104 J°. Lustre vitreous 

 to pearly and greasy. Color pale mountain-green, or sea- 

 green to white. Translucent to subtransparent. H. = 6. 

 G. =3-3-11. 



Composition. A lithium-aluminum phosphate, =41 O s P. 2 + 

 \\ (Li, Na) F. B.B. fuses very easily with intumescence, 

 coloring the flame yellowish red to rich carmine-red, owing 

 to the lithia present, and traces of green owing to the phos- 

 phoric acid. Gives the reaction also for fluorine. 

 Obs. Occurs in Saxony and Norway. 



Hebronite is a closely related mineral from Hebron and Mount Mica 

 in Maine, and from Redding in Connecticut. 



Herderite is supposed to be an anhydrous calcium-aluminum phos- 

 phate with fluorine. 



Durangite. An anhydrous arsenate of an orange-red color, contain- 

 ing aluminum, sodium, iron, and some manganese, with over 7 per 

 cent, of fluorine. From Durango, Mexico, where it occurs with cas- 

 siterite or tin ore. 



Ijazulite. 



Monoclinic. In crystals and also massive, of an azure-blue 

 color. H.=o-6. G. = 3'057. 



Composition. RA1 9 P 2 + aq= Phosphorus pentoxide 46' 8, 

 alumina 34*0, magnesia 13*2, water 6 -0=100. B.B. in the 

 closed tube whitens and yields water ; with cobalt solution 

 the color is restored; in the forceps whitens, swells, cracks, 

 and falls to pieces without fusion, coloring the flame bluish- 

 green. 



Obs. From Salzburg, Styria; Wermlancl, Sweden; Crowder 

 Mount, Lincoln County, N. C. ; and on Graves Mountain, 

 Lincoln County, Georgia. 



