ZINC ORBS. 273 



Composition: silica 25; 1. oxyd of zinc 67*4, water 7*5. 

 Before the blowpipe it slowly intumesces and emits a green 

 phosphorescent light ; but alone it is infusible. Forms a cleai 

 glass with borax. In heated sulphuric acid it dissolves, and 

 the solution gelatinizes on cooling. 



Dif. Differs from carbonate of lime or aragonite by its 

 action with acids ; from a salt of lead or any zeolite, by its 

 infusibility ; from chalcedony, by its inferior hardness and its 

 gelatinizing with heated sulphuric acid. 



Obs. Occurs with calamine. In the United States, it is 

 found at Vallee's Diggings, at the Perkiomen lead mines on 

 the Susquehanna, opposite Selimsgrove, and abundantly at 

 Austin's mines, Wythe county, Va., and Friedersville, Pa. 



Uses, Valuable as an ore of zinc. 



Willemite is an anhydrous silicate of zinc, of a yellowish or brownish 

 color. H=5— °-5 5 Gr=*4 — 41. Occurs in large grayish hexagonal 

 prisms with rhombohedral terminations, at Stirling Hill, N. J., being 

 the mineral formerly called Troostite. Consists of silica 27'1 5, and 

 oxyd of zinc 7285. Also obtained at Moresnet in Belgium. 



Hopeite is a rare mineral occurring in grayish-white crystals or mas- 

 sive, with calamine, and supposed to be a phosphate of zinc. 

 ' Franklinite, an ore of iron, manganese and zinc, is described under 

 Iron, on page 240. 



Aurichalcite is a hydrous carbonate of zinc and copper, occurring in 

 drusy incrustations of acicular crystals, having a verdigris green color. 

 From Siberia, Hungary, England, and Lancaster, Pa. 



GENERAL REMARKS ON ZINC AND ITS ORES. 



The metal zinc (spelter of commerce) is supposed to have been un- 

 known in the metallic state to the Greeks and Romans. It has been 

 long worked in China, and was formerly imported in large quantities by 

 the East India Company. The ores from which it is obtained are the 

 carbonate and silicate of zinc, (calamine and electric calamine,) and to 

 some extent the sulphuret, (blende,) and the oxyd. Blende, the black 

 jack of English miners, was considered useless until the year 1738, when 

 a mode of reducing it was introduced. 



The principal mining regions of zinc in the world are in Upper Silesia 

 at Tarnowitz and elsewhere ; in Poland ; in Carinthiaat Raibel and Blei- 

 berg ; in Netherlands at Limberg ; at Altenberg, near Aix-la-Chapelle 

 in the Prussian province of the Lower Rhine ; in England, in Derby- 

 shire, Alstonmoor, Mendip Hills, etc. ; in the Altai in Russia ; besides 

 others in China, of which little is known. In the United States, tnt 

 calamine and electric calamine occur with the lead of the west in large 



How is electric calamine distinguished from calc spar and chalcedony ? 

 From what ores is the metal zinc obtained 1 What is zinc called in 

 commerce ? When was blende first used in England ? Where are 

 zinc mines in the United States 1 



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