58 



Fig. 4. II vaite, type III. 



Type III 



is also in all essentials like the prin- 

 cipal type. Only very few crystals 

 have been found, all from the same 

 piece ; the size is about 2""". 



The most characteristic feature 

 is that the crystals are highly com- 

 pressed and plate-formed in the direc- 

 tion -L on the 6-axis. Of the prismatic 

 faces s {120} is the only one com- 

 monly found, while Л{210} is very 

 narrow or quite wanting; generally 

 ?6-{30l} is also wanting. /"{041} and 

 e{02l} are developed to almost the 

 same degree. 



Type IV. 



The crystals of this type are of all the forms those least 

 abundant in faces ; they are only found in a few pieces, and 

 always together with small rosettes of haematite; this type is 

 also the only one found together with the haematite, which 

 mineral otherwise, where it is found, seems quite to supersede 

 the ilvaite. The crystals are also, besides 

 the haematite, accompanied by numerous 

 crystals of albite. One single piece is very 

 characteristic, as containing both a cavity 

 with haematite and ilvaite of the present type, 

 and another cavity without haematite, but 

 with large crystals of ilvaite of type VII. 



The crystal is almost exclusively bounded 

 by s {120} and P{lOl}; of the other faces 

 Fig. 5. Ilvaite, typeiv. ^^{gio} and e{02l} are found in most in- 

 stances, but are very insignificant; the other forms are most 

 frequently wanting. 



