C. Palache — Mineralogy of Franklin Furnace, JV. J. 183 



passed through the writer's hands and the data secured from 

 them permit the establishment of a satisfactory axial ratio. 

 The live measured crystals were colorless or pale green prisms 

 terminated by the_base and one or both of the rhombohedrons 

 e (0112) and r(1011). 



Angle e y\ e, 19 readings average 20° 47', limits 20° 35' 

 " c A r, 14 " ^ " " 37° 35', " 37° 20' 



— 21° 04 



-37° 40' 



Whence a : c = 1 : 0-6612 

 Levy " = 1 : 0-6696 

 Dana " = 1 : 0-6775 





Calculated angle, c ^ e = 20° 53' 

 c ^ r = 37° 22 





Refractive indices, measured on a prism || c. 





Sodium light, w = 1*69390 e = 1-72304 

 Lithuim " o> = 1'68897 e = 1-71812 





Friedelite : Occurrence ; Composition. 



Friedelite has not been before described from America. It 

 was identified by the writer on a single specimen from Buck- 

 wheat mine, Franklin Furnace, in the Kemble Collection, and 

 in minute amount on specimens from the Parker shaft. The 

 mineral occurs in scales or tabular crystals with the unit rhom- 

 bohedron and base, not measurable. 



The analysis, with others for comparison, follows : 



1. Friedelite, Franklin Furnace, Schaller, U. S. G. S., 1906. 



2. Same recalculated to 100 per cent after removing H 2 — 



and substituting equivalents of MnO for FeO, MgO, 

 ZnO and CaO. 



3. Average of four analyses of friedelite (Dana, System and 1st 



Appen.) recalculated as in number 2 above. 



4. Theory for H 9 (MnCl) Mn 7 (Si0 4 ) 6 



5. Theory for H 20 (MnCl), Mn 14 Si r; 4a 



6. Theory for H ]6 (MnCl) 2 R X1 Si 10 O 40 (Zambonini). 





1 



2 



3 



4 



5 



6 



Si0 2 



34-69 



3495 



34-14 



34-73 



34-43 



34-84 



MnO 



48-00 



53'22 



54-35 



54-80 



54-33 



53-60 



CI 



3-43 



3-45 



3-42 



3-42 



3-39 



4-12 



H 2 + 



9-08 



9-15 



8-84 



7-82 



8-60 



8-36 



H 2 0- 



1-94 













FeO 



1-45 













MgO 



•98 













ZnO 



1-05 













CaO 



•63 











' 





101-25 



100-77 



100-75 



100-77 



100-75 



100-92 



Less O = 



CI -77 



"77 



'75 



"77 



0-75 



•92 



100-48 100-00 100-00 lOO'OO 100*00 lOO'OO 



