48S S. L. Penfield — Beryllium Minerals from Colorado. 



converted into phosphate. In the filtrate the lime was sepa- 

 rated from magnesia as an oxalate and the magnesia determined 

 as a phosphate. 



The analysis gave the following results : 



•7676 1-00 





1. 



2. 



Mean. 



Ratio. 



Si0 4 .__. 



45-96 



46-15 



46-06 



•7676 



FeO . . - . 



3-56 



3-70 



3-63 



•0504 '} 



ZnO 



7-39 



7-28 



7-33 



■0905 | 



MnO _ _ . 



34-45 



34-11 



34-28 



•4828 y 



CaO 



7 05 



7-03 



7-04 



•1257 | 



MgO— . 



1-22 



1-38 



1-30 



•0325 J 



Total .... 



99-63 



9965 



99-64 





'7819 1-02 



This gives the correct formula for a meta-silicate K SiO s . It 

 does not show however that there is any definite ratio in the 

 isomorphous mixture of the molecules of the different silicates 

 present. 



In closing, the author desires to express his thanks to Prof. 

 G. J. Brush for his kindness in affording the material upon 

 which this investigation was made and to Prof. S. L. Penfield 

 for valuable assistance and advice. 



Mineralogical Laboratory of the Sheffield Scientific School, 

 New Haven, Conn., May, 1890. 



Art. LXIY. — Some Observations on the Beryllium Minerals 

 from Mt. Antero, Colorado ; by S. L. Penfield. 



During the past few years crystals of beryl, bertrandite and 

 phenacite have been abundantly found associated with one 

 another at Mt. Antero and Mt. White, one of its spurs. They 

 are either implanted on granite or on crystals of the granitic 

 minerals quartz and feldspar, but to my knowledge no very 

 exact data regarding the occurrence of the minerals has been 

 obtained. Owing to the great number of specimens which 

 have been collected, the beauty of the crystals as well as the 

 interesting crystallization of the rare bertrandite and phenacite 

 these minerals have been of unusual interest to mineralogists. 



1. Beryl. 



It is almost certain that beryl is the parent mineral which 

 has furnished the beryllium for the bertrandite and phenacite 

 as both of these occur associated with and frequently implanted 

 on beryl crystals. The beryl occurs in transparent light green 

 and blue prismatic crystals of the aqua-marine variety. They 

 are usually very simple, combinations of the hexagonal prism 

 1010 and base 0001 being most common, while occasionally a 

 pyramid of the second order 2-2, 1121 and the dihexagonal 



