Laboratory of the Sheffield Scientific School. 289 



II. On a Rhodonite (Foiderite) Crystal from Franklin, 

 N. J. ; by W. E. Ford and R. D. Crawford. 



The Brush Mineral Collection recently acquired through 

 Mr. Lazard Cahn two specimens of crystallized rhodonite from 

 Franklin, N. J. The crystals, while showing in general the 

 characteristic habit of rhodonite from this locality, were uncom- 

 monly rich in planes and were of sufficiently good quality to 

 admit of measurement on the 

 reflection goniometer. One of Fig. !• 



the specimens, which was a de- 

 tached crystal, was studied in 

 detail. Since the results showed 

 the presence of one new face and 

 of another that has been listed as 

 a doubtful form, it seemed worth 

 while to publish a figure with a 

 brief description of the crystal. 



The crystal, represented as 

 nearly as possible in its true pro- 

 portions and development in fig. 

 1, measures about 2 cm in its great- 

 est dimension parallel to the b 

 crystal axis and about l*5 cm par- 

 allel to the c axis. The forms 

 present are as follows : a (100), 

 * (010), c(001), m(110), M (110), 

 A* (401), ,9(201), 2(221), m(Ill), 

 A (321), *(441), r(lll), I {US), 

 w(221), and also «(221) and 

 -0(04:1). The last form t>(041) 

 has never, so far as has been dis- 

 covered,been previously recorded 

 on rhodonite. It occurred as a 

 small face, and because of its 

 poor quality did not give a veiy 



sharp signal when measured on Fig. 1. Rhodonite, Franklin, N. J. 

 the goniometer. Its identity was 



however established by the fact that it lay clearly at the inter- 

 section of two well-defined zones on the crystal, namely, 

 J (010) -<? (001) -6(010), and J/(110)-?i((221)-"j/(110). The 

 angle c (001) : v (041) was measured as accurately as possible, 

 giving 77° 35'-; calculated, 77° 5J'. 



The pyramid k (221) has been described by Hamberg as 

 occurring on rhodonite from the Harstigen mine near Pajs- 

 berg, Sweden.* As, however, the measured angle of c(001) : 



* Geol. For. Fi>rh., xiii, 565, 1891. 



