386 Genth and Penfield — Contributions to Mineralogy. 



4. The fragment is part of a modified tetra- 



hedron, having the forms o, 111, 1 ; o', 111, 

 — 1 and d, 110, i, fig. 4. One of the dodeca- 

 hedral faces is larger than the other two 

 and, as it makes a right angle with the large 

 tetrahedral faces adjacent to it, it gives the 

 crystal the appearance of being part of a 



modified cube. 



No cleavage has been observed ; fracture uneven, splintery 



to subconchoidal, color of some portions pale rose color to 



brownish, owing to slight oxidation. Sp. gr.= 3 626 to 3'661. 



Luster vitreous. 



The material used for analysis was purified by digesting 



with very dilute hydrochloric acid and had a fine pale rose 



color, like a deeply colored rose quartz. The mean of two 



closely agreeing analyses is as follows : 



Mol. ratio. 



2-93 



6-90 



1-00 



Ignition . 



Si0 2 



BeO 



CuO 



ZnO 



FeO 



0-21 

 30-26 

 12-70 



0-30 



46-20 



.. 6-81 



Si .... 

 Be ... 

 Cu ... 

 Zn... 

 Fe.... 

 Mn... 



2-78 



14-12 

 4-70 

 0-24 



37-07 



5-37 

 0-95 



32-26 



•504 



•500] 



•004 1 



•570 } 1-187 

 •096 J 



MnO.. 



S 



1-22 

 5-49 



•01 7 J 

 •172 



Less for S . 



103-19 



.. 2-78 









100-4] 

 .. 35-04 



2-016 



11-72 



closely agreeing with the formula : 



(Be, Zn, Fe, Mn) 7 Si 3 12 S 



Associated with quartz, astrophyllite and a mineral which 

 appears to be new. 



7. Yttrium- Calcium Fluoride. 



On some of the quartz associated with astrophyllite was a 

 mineral in granular crystalline particles. Some fragments 

 show reflections from cleavage planes. White, grayish white 

 and reddish white. H.= 4. Sp. gr. = 4-316. 



In the analysis of the best fragment which I could get, a 

 little over one gram, the mineral was decomposed by sulphuric 

 acid, by which the fluorine was expelled as HF1 and the little 

 silica as SiFl 4 . The analysis gave : 



