214 Kraus mid Cook — Iodyrite from Tonopah. 



w'{ 9092 }, y{9091}, and 2/'{9091[. Of these forms m|1010f 

 predominates. The lower pyramid, ^ v 1 2021 } , is also rather 

 large. The upper basal pinacoid, cJOOOIJ, is usually next in 

 size. The other forms generally occur as rather narrow faces. 

 The relative sizes of the faces of the various forms are clearly 

 shown in figure 2. Of the forms observed on crystals of _this 

 type,_it is well to point out that *|7073}, w{9092}, w'{9092}, 

 2/{ 9091 } ? and y'{9091[, are all new. The close agreement 

 between the calculated and observed values for these new 

 forms makes us feel confident that they are to be considered 

 as established. 



Type 2. A pyramidal habit is a striking characteristic of 

 crystals of this type. The following forms were noted on 



Figs. 2-5. 



them : cjOOOl 



c/5 



15.0.15.8 



, c'jooo: 



Of these forms s' 



* -J 2021 



2021 L and 



15.0.15.8 £ was observed for 



the first time. The general character of crystals of this type 

 is shown in figure 3, which consists of a combination of the 

 forms just enumerated. Hemimorphism is very pronounced 

 on these crystals. 



In several instances on crystals of types 1 and 2 the 

 additional new forms were noted: r\70 f t4:\, a? {7071}, and 

 2 {33.0.33.2}. These forms are usually to be observed as very 

 narrow faces, and as they do not occur often, we did not deem 

 it necessary to figure them. 



Type 3. Crystals of this type of development are not 

 very common. They possess a tabular habit and are appar- 



