HABIT. 



57 



Habit 1. The wedge-shaped crystals are generally striated in the 

 prism zone with the forms a{100}, Z{210}, and ra{110} grading into 

 one another, as shown in figure 9. On many crystals, however, the 

 in< 1 i v i( 1 ual prism faces are sharply separated and commonly yield single 



FIGURE 3. Ixmg, narrow, wedge-shaped crystal of habit 1, the most frequently observed habit. Forms: 



c{001}, n{100>, 77i{110>, f{210>. 



FIGURE 4. Short, prismatic, somewhat flattened 

 crystal of habit 2. Fairly abundant. Forms: 

 c{001>, 6{010>, a{100>, 7n{110>, 



FIGUEE 5. Tabular crystal of habit 3. Common 

 habit for contact twins, but rare for single crys- 

 tals. Forms: c{001}, 6{010}, a{100>, m{110}, 

 Z{210>. 



FIGURE 6. Cubic crystal of habit 4. Rare. Forms: 

 c{001>, 6{010>, a{100>, 



FIQUBE 7. Rhombic crystal of habit 5. Fairly 

 abundant. Forms: b{ 010}, a{ 100}, /{ 102}. 



distinct reflections. Figure 10 (crystal 4) also represents a typical 

 crystal of this habit. On removing these crystals from the matrix, 

 to which they are firmly attached, they usually cleave, and the result- 

 ing loosened crystal piece will consequently be much shorter in the 



