136 



BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



are the average of a number which were made with the re- 

 flecting goniometer on several crystals, the rounded char- 

 acter of the faces sometimes introducing errors of as 

 much as 30': 



Calculated. 

 68 30' 



m : m (front) 110 

 m : m (back) 110 



no 



m : b (front) 



(110 

 : 6 (back) ] 



(1W 



110 



ilo 



010 



0103 



010^ 

 010) 



Measured. 

 68 49' 

 68 41 



55 40 



55 50 



68 30 

 55 45 



55 45 



The terminal faces were too much rounded to permit of 

 measurement. The clino-pinacoidal cleavage is almost 

 micaceous in perfection and the pyramidal cleavage (n) is 

 well developed. There was no case of twinning observed. 

 The hardness is 2. Ignited on charcoal in RF the powder 

 of the mineral glows and yields an alkaline residue. 

 Moistened with hydrochloric acid and introduced into the 

 flame of the Bunsen burner it shows the calcium flame. 

 The optical orientation of the mineral was found to agree 

 in every respect with that of gypsum. Since the examina- 

 tion of this mineral was made, Prof. Kremers of this uni- 

 versity has shown me a very similar specimen from Mineral 

 Point which was brought to him labelled "anglesite. " It 

 is therefore almost certain that the mineral which has 

 been referred to as "anglesite" from Mineral Point in the 

 state reports is really gypsum. These references are al- 

 ways very indefinite, and usually state that the mineral is 

 "reported" or is "said to occur" at the locality. No de- 

 termination of the supposed anglesite seems to have 

 been made. 



