EXPLA.NATION OF PLATE VII. 



(iLADBERITE CRYSTALS AND OpAL PsEUDOMORPHS, WhITE ClIFFS, 



N. S. Wales. 



Forms:— r (001), -t (111). » (111). 

 Fig. 1. Projection on (001) of a glauberite crystal showing the forms s 

 (111) andw (111). 

 ,, 2. The same, with oscillation of (131) on v and of c on ». 



„ '.^, Freehand drawing of a pseudomorphic opal crystal in similar 

 position and showing the trace of the basal cleavage on » 

 and striations supposed to be due to oscillatory combination 

 of s with (131). 



i. Projection of a glauberite crystal on a plane perpendicular to 



the zone axis s.s'. 

 5. The same with traces of basal cleavage and (131) oscillating with v 



3. Freehand drawing of pseudomorphic opal crystal in similar posi- 

 tion showing cleavage traces. 



7. Projection of glauberite crystal on (010). 



S. The same with oscillation of (131) on » and of c on ?i. 



3. Freehand drawing of pseudomorphic opal crystal in similar 

 position showing striations on -t and cleavage traces on n. 



Note. — »' in the right hand half of fig. 4 should read »", and in the left 

 hand half n". 



