180 C. Palache— Mineralogy of Franklin Furnace, J¥. J. 



Franklinite: Form, Composition. 



Small implanted crystals of franklinite of quite abnormal 

 appearance were seen in two specimens believed to have come 

 from the Hamburgh mine, Franklin Furnace. The crystals 

 are of adamantine luster and on edges or where splintered 

 show a deep red color. The prevailing habit is cubo-octahe- 

 dral with occasional planes of the forms (101), (311), (211) and 

 (310). The unique color and habit of these crystals suggested 

 a new type of the spinel group, but the analysis below by W. 

 T. Shaller, IT. S. G. S., shows them to be of ordinary frank- 

 linite composition. Specific gravity 5*09. 



*Fe 2 3 .____ 



*MnO 



ZnO 



66-58 



9-96 



20-77 



CaO 



MgO 



HO 



0'43 

 0-34 

 0*71 









99'51 

 Hetmrolite: Form, Composition. 



Reexamination of this mineral, which has been a doubtful 

 species because of Moore's incomplete description, establishes 

 the correctness of his characterization as a zinc hausmannite. 



Tetragonal, shown by optical behavior of the fibers under the 

 microscope. Indistinct prismatic cleavage, specific gravity 4*85. 



Composition ZnO.Mn 2 3 , as shown by the following analysis 

 of material furnished by E. P. Hancock : 



1. Hetgerolite, analysis by W. T. Schaller, U. S. G. S., 1906. 



2. Same corrected for the small amount of Si0 2 and for 

 water probably contained in a slight admixture of chal- 

 cophanite. 



1 2 Ratio. 



MnO 60-44 63-85 "405 



FeO ... -77 083 -005 r 



ZnO" 33-43 35-32 -4 35 1*06 



Si0 o ._ 1-71 



H 2 0- 2-47 



H + 1-42 



100-24 100-00 



Hausmannite, MnO.Mn 2 O a 

 Hetaerolite, ZnO.Mn 2 3 



Pyroxenes: Composition. 



Manganese- and zinc-bearing varieties of pyroxene are char- 

 acteristic both of the granite and of the intruded rocks near 

 the contacts at Franklin Furnace and Stirling Hill. The dis 



* State of oxidation of iron and manganese not known. 



