68 JOURNAL OF THE 



Water, loss on ignition, 5.46 



Silica, 45.40 



Titanic acid, . • 1.10 



Alumina, 33.66 



Ferric oxide, 2.36 



Magnesia, 1.86 



Lithia (trace), 



Soda 1.41 



Potash, 8.33 



Fluorine, .69 



100.27 

 Less oxygen, .29 



99.98 



Associated with and upon it, were found thin scales of a min- 

 eral related to hisingerite; it may be "giliingite.'^ 



Dolomite. — Beautiful crystallizations, of this carbonate of 

 magnesia and lime, occur with siderite (carbonate of iron) and 

 calcite (carbonate of lime) in the gem-bearing pockets of the 

 deeper w^orkings in the Emerald and Hidden ite mine, in Alex- 

 ander county. The crystals are remarkable for not presenting 

 any curved faces and for their simplicity of form. Tlie unit or 

 cleavage rhonbcjhedron is the common form, though four other 

 planes have been observed. Twin crystals are common. Color, 

 from clear glassy colorless to pale brown and purplish. White 

 opaque crystals are also found. No finer crystals of dolomite 

 have been discovered in the United States, and few, indeetl, from 

 European localities can compare with them. 



Smooth polished crystals three inclies in diameter were not 

 uncommon. Outside of this Alexander county region no crys- 

 tallized dolomite had been found before in this State, and only 

 near the valley river in Cherokee county, as a marble-like 

 variety, is its existence otherwise known in the State. 



Gahnite (zinc-si)inel). — Dr. Genth has analyzed the fine green 

 massive variety from the Grassy Creek mica mine, in Mitciiell 

 county, and found it to contain thirty-eight per cent, of the 

 oxide of zinc, which is uncommonly high for the mineral. Con- 

 sidering its rarity and mode of occurrence the liigh per cent, of 

 zinc found in it seems to have been discovered in a verv odd and 

 out-of-the-way place. No other zinc mineral is known to exist 

 in the neighborhood or for many miles around. 



