from San Luis Potosi, Mexico. 



185 



parent. These proved to be isotropic, and since they showed 

 no evidences of crystal form or cleavage, the mineral is prob- 

 ably amorphous in character. 



Fig. 1. 



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It was at first thought that the material of the pseudomorphs 

 would prove to be a simple antimony oxide, perhaps cervantite. 

 But the analysis showed, however, that notable amounts of 

 water and lime were present. The method of analysis was 

 briefly as follows : The finely powdered mineral was thor- 

 oughly fused with sodium carbonate. This fusion was dis- 

 solved in hydrochloric acid, and the antimony precipitated as 

 the sulphide by hydrogen sulphide gas. The precipitate was 

 collected on asbestos in a filter tube, ignited in a current of 

 hydrogen sulphide, and weighed as Sb.,S 3 . The calcium was 

 precipitated in the filtrate by ammonium oxalate, and weighed 

 as CaO. The water was determined by ignition, and in one 

 case this result was checked by making a direct weighing of 

 the amount of water set free wheii the mineral was ignited in 

 a closed glass tube. During the analysis the absence of MgO, 

 A1„0 3 , and Si0 2 was proved. 



