46 
saloon, particularized those relative to colour, viz. the 
Nat. Hist, yellow, the brown, and the black blende of Wer- 
ner; the first of which is generally most pure, 
while the two others contain a portion of iron ; 
the variety called testaceous blende (Schaalen 
blende), the most characteristic specimens of 
which are from Geroldseck in the Brisgau, con- 
tains, besides iron, a portion of lead. — The other 
ores of zinc in this case are those of a sparry 
appearance, commonly called calamine, which 
Mr. Smithson has ascertained to constitute three 
different species, viz. the electric or quartzy cala- 
mine, which becomes strongly electric by heat; 
the common calamine, or native carbonate of 
zinc; and the hydrous carbonate of zinc: the 
specimens of the two former species include 
various crystalline and other forms, among 
which are the pseudomorphous crystals of car- 
bonate of zinc, derived from modifications of 
calcareous spar. 
(Case 41.) Ores of tin, of which we have the 
sulphuret of tin, or tin pyrites, and the oxides, 
which are divided into common tin stone, and 
wood tin : — tin pyrites, hitherto only found in 
Cornwall, nearly pure, mixed with copper pyrites, 
he. ;— among the specimens of common tin stone 
may be particularized the regular and macled 
crystals^ 
