312 



University of California. 



[Vol. i. 



EXPLANATION OF PLATE 17. 



m = | no | 

 d — [on j 

 d' — {041} 

 o — -J 001 1 

 b — { OI °} 



Figure 1. — Common habit of lawsonite when crystallizing freely in open 

 clefts. 



Figure 2. — Frequent habit of small crystals. 



Figure 3. — Crystal fragment, showing occurrence of the rare brachydome 

 face d' =041. 



Figure 4. — Diagrammatic plan of twin crystal, showing strict on basal pina- 

 coids, positions of axial planes, and reentrant angle. 



Figure 5. — Twin of the habit common in larger crystals embedded in mar- 

 garite. Twinning and composition plane the prism. 



Figure 6. — Habit commonly affected by larger crystals embedded in mar- 

 garite, showing characteristic direction of elongation. 



Figure 7. — Habit of large crystals in matrix of margarite. 



Figure 8 — Twin of the habit common in smaller crystals. 



