294 PHYSIOGRAPHY. CLASS n. 



Fundamental form. Scalene four-sided pyramid. 

 P = 120 27', 118 39', 90 47'. Vol. I. Fig. 9. 

 LEONHARD. 



Simple forms. P QD (P) ; P + QD (M ) = 91 

 33'; ?r(0 = 10928'; Pr = 1080'; Pr+x. 



Char of Comb. Prismatic. 



Combinations. 1. P oo. P + OD. 2. ?r. P -f oo. 

 3. P QD. Pr. P 4- oo. Fig. 3. All of them 

 from Lisenz, Tyrol. 



Cleavage. P + QD very distinct, often covered 

 with scales of mica ; Pr -f- QD more smooth and 

 shining, but interrupted and less easily obtain- 

 ed. Traces of Pr, and Pr + OD, the latter 

 scarcely perceptible. Fracture uneven. Surface, 

 uneven and rough, seldom smooth. Generally 

 covered with plates of mica. 



Lustre vitreous. Colour flesh- red, passing into 

 pearl-grey. Streak white. Translucent on the 

 edges. 



Hardness 7-5. Sp. Gr. = 3-104 of a cleavable 

 variety. 



Compound Varieties. Massive : composition 

 indistinctly granular and columnar. 



OBSERVATIONS. 



1. Among the minerals which accompany the prismatic 

 Andalusite from the Tyrol, there is one which possesses 

 its form, but none of its other properties. Its hardness 

 is ss 5-0, the specific gravity = 3-543 ; besides, the crystals 

 are compound, and seem to be pseud omorphic, perhaps be- 



