304 Hidden and Mackintosh — Occurrence of Poly erase. 



Oxygen ratio. 



Cb 2 6 ) (28-52*) ( ) 



Ta 2 O a [ 48-91 ) [? \?[ 



Ti0 2 ) (20-27t) ( ) 



Y 2 3 , etc 27-55 At. w't. = 103-8 32-37) 



Fe 2 3 3-19 6-00 V 52*71 



U0 3 _._13-77 14-34) 



H 2 (Ign.) 5-18.. 28-83 



98-48 f 



The analysis was conducted in general after the method of 

 J. Lawrence Smith, using hydrofluoric acid. The mineral is 

 completely soluble in boiling sulphuric acid when very finely 

 powdered. 



An H 2 S0 4 solution of both these minerals show, when HC1 

 and metallic zinc are added, at first a faint violet color then 

 momentarily a deep sapphire-blue which changes to greenish 

 and finally to a deep brown. The solution then .clears and a 

 muddy precipitate forms. The reactions are quite similar to 

 the behavior of the Hitteroe polycrase. 



The foregoing statements comprised our data of this mineral 

 up to the discovery, in September last, of another occurrence 

 of the same species on a more satisfactory scale. Whereas we 

 had formerly a few grams we now have ounces, and where be- 

 fore we had small pieces of impure material we now have large 

 crystals of almost normal purity. The alteration-products are 

 also now available for separate examination, and our present 

 supply of crystals includes many that weigh from 5 to 10 grams 

 each and one of one ounce. All have the same habit as those 

 first described. Some, as before stated, are quite pure, while 

 others are almost wholly changed into a lemon-yellow gv/mmite 

 which has Sp. Gr. = 3'33+. Hardness=3*5. Loses 11*46 per 

 cent after ignition and becomes dull-brown. When oppor- 

 tunity offers we intend looking into it more thoroughly. 

 Minute radiated tufts of what may prove to be tengerite were 

 also noticed in the clefts of the mineral. 



The new material unfortunately does not offer smooth enough 

 surfaces for exact measurement of angles. The crystals pre- 

 sent the macro- and brachypinacoids as predominating planes, 

 with the brachypinacoid usually the larger. One brachyprism 

 (i-3) ; two brachydomes (l-i, 2-1) ; one brachy diagonal pyra- 

 mid (1-3) ; and one macrodome (-J-?), which latter is new to 

 the species. Several specimens of a twinning parallel to the 

 new macrodome were observed ; this is peculiar for the reason 

 that at the first locality the only twin observed was parallel to 



* This gave the blue reduction test with zinc. 



f This gave the violet test by reduction with zinc. 



