"The pyramid h has, however, sucli minute faces, that accurate meas- 

 urements w^ere impossible. 



" With great attention I treated the question whether our mineral be 

 rhombic or monoclinic, having at my disposal a good crystal allowing 

 measurements on one side as well as on the other side of the a.^ls a 

 (brachydiagonal). I found : 



o : o (in front) 

 o • o (behind) 



120O 52' 

 126 53 

 126 55 

 126 56 



Considering the development of the faces, this diflference does not exceed 

 the probable error. Besides, not having observed any indication of 

 twinning, I thought it necessary to maintain the rhombic system, adopt- 

 ing Des Cloizeaux's opinion. Supposing Websky's views to be correct, 

 the calculation of the two mentioned angles would give the following 

 results : 



o : o (in front) = 126° 43' 



o : o (behind) = 126 16 



a difference which cannot exist in our crystals. 



"The development of the New Mexican descloizites is different, as our 



figures 1-4 will show : 



"Fig. 1 represents crystals of a dark 

 "red color (implanted), attached on a 

 "quartzitic gangue which is covered 

 "with psilomelane. The crystals reach 

 " 2"'"" in size and are very bright. A 

 "specimen of this kind was used for 

 " the measurements. The faces f are 

 "striated and dull. 



