120 



C. H. Warren — Mineralogioal Notes. 



m, 1010 

 <?, 0112 



ft, 0221 

 .9, 21 §1 



s„ 3121 



The development of the faces is shown in Fig. 3, which 

 represents the smaller crystal weighing 2 lbs., and measuring 

 4^ inches in diameter, and Fig. 4, representing a crystal 12 

 inches in diameter, and weighing 28 lbs. If the faces had been 

 symmetrically developed in about the proportions represented by 

 these two partial crystals, the complete form would appear like 



Fig. 5, which differs from previously described crystals of 

 phenacite, in that the /x, s and s 1 faces are unusually prominent, 

 while, when prismatic forms are developed, generally the prism 

 of the second order a is prominent instead of m. 



Owing to the rough character of the faces, only approximate 

 measurements could be made with the contact goniometer, and 

 these are given in the accompanying table, together with the 

 values calculated from the measurements of Koksharov* 



Measured. Calculated. 



m^m, 1010/vOllO = 60° 60° 



d /^ d, 0112^1102 = 36 35 58f 



m ^ fi, 0110^0221 = 33 33 14~ 



m^/x, 1010^0221 = 66 65 16j 



fi ^ /x, 0221^2201 = 92 92 50 



m zv 5, 1010^2131. — 33 32 8 



d /s s, 0112^2131. = 50 48 59 



s ^ s l ,213\^312l = 35 34 2 



A determination of the bases w T as made on a portion of 

 material which was decomposed by hydrofluoric and sulphuric 

 acids, and gave the following results : 



A1 2 3 19-30 



Fe 2 3 -54 



Li 2 -68 



Na 2 1-17 



K 2 0.._ _ - -67 



H 2 .- 5-58 



27-89 

 Quartz and combined silica by difference ._ 72*1 1 



* Materialen zur Min. Russland, ii, p. 308, 1857 



