COMMUNICATIONS FROM THE HARVARD MINERALOGICAL 



MUSEUM. 



VIL — ON HARDYSTONITE, A NEW CALCIUM-ZINC SIL- 

 ICATE FROM FRANKLIN FURNACE, NEW JERSEY. 



By John E. Wolff. 



Presented March 8, 1899. Received March 13, 1899. 



In the fall of 1898, while studying the ore deposit in the new work- 

 ings at North Mine Hill, Franklin Furnace, in connection with the Frank- 

 lin Folio of the United States Geological Survey, the writer took down 

 from the wall of a cross-cut at the extreme north workings, and about 

 900 feet below the surface and near the limestone foot-wall, a specimen 

 of ore composed of small irregularly interlocking grains of green and 

 reddish willemite, lilac-brown rhodonite, franklinite in abundance, and 

 a white mineral which is the subject of this paper. The ore is banded, 

 and the grains average about a millimeter in diameter. 



Chemical Composition. — Part of the specimen was pulverized and 

 passed through a 90-mesh sieve, the franklinite and rhodonite taken out 

 by the electro-magnet and portions of the white mineral obtained by 

 careful hand-picking, which were then purified from a trace of calcite 

 by the Thoulet solution, but still contained a few specks of franklinite 

 and an occasional grain of willemite. The following analyses (I. to IV.) 

 were made on separately picked portions : — 



I. II. III. IV. 



1.59 



0.86 



For the iron and manganese determination of IV. over a gram of 

 material was used which had been separated from the willemite, etc., by 



