2 Description of STERNBERGITE, 



known in the species, were dug up so late as 1817 and 1822. 

 The National Museum at Prague possesses one of them, consist- 

 ing of a group of crystals several inches long, without having 

 any rock attached to it, and weighing about twelve marks, or up- 

 wards of six pounds Avoirdupois, the value of the silver of which 

 is more than L. 16 Sterling. 



It was in the same collection that I first observed a variety 

 of the species of Sternbergite, which it is the object of the pre- 

 sent paper to describe. Professor ZIPPE, the keeper of the mu- 

 seum of natural history, directed my attention towards it, as be- 

 ing something he could not bring under any of the species al- 

 ready known ; and as it appeared an interesting mineral, I re- 

 quested his permission to take it with me to Edinburgh, in or- 

 der to examine its forms, and other properties, a request which 

 was readily granted. Gubernialrath NEUMANN of Prague, late 

 Professor of Chemistry there, was not less liberal in allowing 

 me to take with me the only specimen of it contained in his 

 collection, where it had been designated by Mr ZIPPE as a, pinch- 

 beck-brown problematical fossil, crystallised in six-sided tables. The 

 crystals in this specimen are very distinct ; they are aggregated 

 along with crystals of red silver in drusy cavities in quartz, which 

 protected their edges from being rounded off by rubbing, like 

 the specimen from the collection of the National Museum. 

 Here, too, the Sternbergite is associated with red silver, and with 

 brittle silver, making the whole highly valuable as an ore of sil- 

 ver. It is likely that most of the specimens have long ago been 

 melted down ; perhaps some of them may yet be discovered in 

 the Imperial cabinet in Vienna, which contains a great number 

 of specimens from Joachimsthal. Professor ZIPPE informs me, 

 that he has found another specimen of the substance in the Mu- 

 seum at Prague, since I had the pleasure of inspecting it in his 

 company. 



