Thaller — Ferritungstite, a New Mineral. 161 



lrt. XVI. — Ferritungstite, a New Mineral ; by Wajldemar 



T. ScHALLEK. 



A sample of tungstic ocher was collected in the State of 

 Washington by Mr. Howland Bancroft, of the U. S. Geologi- 

 cal Survey. The exact locality is the Germania Tungsten 

 Mine, Deer Trail mining district, northeastern part of the 

 State of Washington. Mr. Frank L. Hess, also of the U. S. 

 Geological Survey, suggested that the tungstic ocher might 

 prove of sufficient interest to warrant careful study. On micro- 

 scopic examination, the earthy looking ocher was found to be 

 well crystallized and pure and chemical tests showed that the 

 ocher was a hydrous ferric tungstate, entirely different from 

 ordinary tungstic ocher, called tungstite, which, as Walker* 

 showed, has the formula W0 3 H. 2 0. For the privilege of 

 describing this interesting new mineral, I am indebted to the 

 two gentlemen above named. 



Examination under the microscope shows that ferritungstite 

 crystallizes in hexagonal plates, evenly developed but very 

 minute. Those lying flat on the base are isotropic under 

 crossed nicols, but are too small to exhibit any interference 

 figures. Such crystals as are partially tilted, show decided 

 double refraction on their edge. A small quantity of gangue, 

 mostly quartz, is mixed with the mineral but limonite stains 

 are almost absent, though occasionally a little can be seen. 



Ferritungstite results from the oxidation of wolframite and 

 is associated with that mineral in massive quartz. The cleav- 

 age, hardness and density of ferritungstite could not be deter- 

 mined. The color is pale yellow to brownish yellow when 

 pure. It gives off water in a closed tube, and is decomposed 

 by acids, yellow oxide of tungsten separating out. 



Only a few tenths of a gram of pure material were available 

 for analysis. Two samples were collected at different times 

 from the same specimen. Qualitative tests showed the absence 

 of Mo0 3 ,S0 3 ,P 2 6 , and, in general, of substances other than 

 those given in the analyses. The analyses of the two samples 

 are given below. 



Analyses of ferritungstite. 



1 2 



WO, 37-1 35-8 



Fe 2 3 26-6 27"3 



H 2 0('lgn.) 18-6 20-9 



Insol 14-7 [16-0] 



97-0 100-0 



* This Journal (4), xxv, 305, 1908. 



