184 GEOLOGICAL RECONNOISSANCE 



amorphous, yellow, soft variety of smithsonite; powder of dirty cream- 

 color. 



Occurs in fissures in dolomite. 



Composition of air-dried ore: 



Silica • 2.367 



Sesquioxide of iron . 2.750 



Oxide of zinc 55.238 



Sulphuret of zinc- • '• 0.328 



Lime 2.158 



Magnesia 1 .065 



Carbonic acid and water 34.738 



98.644 

 55.238 oxide of zinc contain 44.334 metallic zinc. A very good ore for 

 smelting, intermediate between ?so. 4 and No. 3, of the Bath mine. 



No. 55. iua?dve smithsonite, from Mr. Smith's land, township 17, 



range 2 west, section x0, Lawrence county. 



A massive, soft, earthy rock, of white, reddish-white, and pale-yellow 

 color, containing amygdaloidal cavities, which are, in part, filled with 

 incrustations of botryoidal smithsonite; the surface of the latter fre- 

 quently covered with a thin layer of peroxide of iron. The rock contains 

 crystals of galena imbedded. 



Composition of the earthy, air-dried ore: 



White sand, and clay (?) 26.454 



Sesquioxide of iron, and alumina 2.193 



Oxide of zinc 27.600 



Sulphuret of lead 0.793 



Lime 8.048 



Magnesia 3.260 



Carbonic acid, water, and loss 31.652 



100.000 

 27.600 parts of oxide of zinc contains 22.15 parts of metallic zinc. Not 

 a rich ore, but equal to the Silesian ore No. 11, of the table on page 156. 



No. 56. Smithsonite, from the Koch mine. 



For the subjoined analysis, pieces of the pure, botryoidal smithsonite 

 were taken, which occur as an incrustation on the compact ore. 



Concentric incrustation, internal structure semi-fibrous; color yellowish- 

 gray, the outermost layer dirty reddish-gray; hardness between 4 and 5: 

 fracture conchoidal; lustre vitreous; subtranslucent; brittle. 



