PHYSIOGRAPHY. 



Albite. 



Cleavage, parallel to P perfect; parallel to the faces M 

 and T less perfect, though frequently obtained with suffi- 

 cient precision to admit of the application of the reflective 

 goniometer. 



Fracture uneven, imperfectly conchoidal. 



Surface slightly rough or streaked upon some of the pri- 

 mary faces, but even. 



Lustre vitreous, often inclining to pearly upon perfect 

 faces of cleavage. Color white, passing into grey, red and 

 green. Streak white. Transparent in small crystals,... 

 translucent on the edges. A bluish opalescence is some- 

 times observable. 



Brittle. Hardness = 2*613 (small transparent crystals 

 from Datiphiny.) Limits 2-61 . . . 2-68. 



Compound varieties. Twin-crystals. Axis of revolu- 

 tion perpendicular to the prismatic axis. 



Fig. 3. 



Fig. 4. , 



