nOBBS — MINERALOGY OF WISCONSIN. 131 



The following measurements were made to identify the 

 above forms: 



Many of the crystals have their faces studded with nu- 

 merous small lenticular yellow crystals with much rounded 

 faces, which are probably siderite. 



The best cerussites which I have examined from Mineral 

 Point are found, like the Highland crystals, on skeleton 

 octahedrons of galena. Some of the smaller crystals have 

 very sharp faces, and so far as examined they appear to 

 have the same forms and habits as the Highland crystals. 



Type 3. Crystals ivith domed liabit. The large gray cer- 

 ussites which come from Galena and Mineral Point, are 

 less perfect and less highly modified than the types just 

 described. The faces reflect poorly, but the following 

 goniometer readings were made on crystals bounded by the 

 forms i, x, m, and subordinate p, this being apparently the 

 usual habit. (See plate 7, figure 3.) 



p : i>, (with front lens) 



These crystals are as frequently simply twinned as the 

 Highland crystals. Their form is represented in plate 7, 



