PHYSIOGRAPHY. 



Albite. 



Twin-crystals, like the above figures, and others still 

 more complicated, are of frequent occurrence, compared 

 with simple forms. 



Massive : composition granular ; individuals of various 

 sizes, commonly compressed parallel to T, in which case 

 the composition assumes a lamellar appearance ; the lam- 

 ellae being arranged somewhat in a stellular manner. The 

 composition rarely approaches the impalpable, in which 

 case it becomes strongly coherent. 



1. Before the blow-pipe on charcoal, it becomes glassy, semi-transpa- 

 rent and white ; but rneits with difficulty only on its edges into a semi- 

 transparent, vesicular glass. It is dissolved by borax, but slowly and 

 without effervescence. If the borax be previously mingled with oxide 

 of nickel, the resulting globule will present a brown color. 



2. Analysis. 

 By EGGERTZ, By ROSE, By STROMEYER, 



from Finbo. from Arendal. from Chesterfield, Mass. 

 Silica . 70-48 . 68-84 . . 70-68 



Alumina . 18-45 . 20-53 . . 1980 



With a little oxide of 



iron and liine. 

 Soda . 10-50 9-12 . . 9-06 



Lime . 55 . 0-00 . . 023 



Oxide of iron & ^ 



manganese 



3. Albite is found entering into the composition of granite, either along 

 with quartz and mica, or accompanied by feldspar. In general, it 

 would appear, that in those granite veins and beds, where Tourmaline 

 abounds, Albite is substituted for feldspar. Albite is also one of the con- 

 stituents of sienile and greenstone. 



4. The largest crystals of Albite hitherto known, are from Kerabinsk 

 in Siberia. Crystallized varieties are found also in the highest districts 

 of St. Gothard, and the Alps of Savoy. The foliated, massive, and near- 

 ly impalpable varieties, occur at Chesterfield and Goshen, (Mass.) asso- 

 ciated with Tourmalines of various colors, as also at Paris in Maine ; at 

 the former places, small transparent crystals, lining cavities ift the ma- 

 shre variety, rarely present themselves : in Middletown, Con., at Ha*i 



i* 



