Mr. William Phillips on the OxydofTin. 339 



Those specimens which heretofore were called native tin, are now 

 generally believed to have been accidentally left by the smelters 

 of the ore, and wherever it is discovered, the place may fairly be 

 supposed to be the site of a smel ting-place. It has now obtained 

 the name of Jews-house tin. 



The oxyd of tin is rarely found in Cornwall free from an 

 admixture with other substances, but in this state it has been 

 produced in masses of considerable size. From the mine called* 

 Polberrow in St. Agness, one block of tin ore was raised weighing 

 12001bs. which produced more than one half of metal. The oxyd 

 of tin seems to occur almost uniformly in a state of crystallization, 

 with whatever substances it is intermingled, or however minute its 

 portions, in the common tin-stone of the mines. It is rarely found 

 in shapeless masses, except, indeed, the rounded grains of alluvial 

 deposition ; and even amongst these many appearances of crys- 

 tallization, but mostly of the made, may be noticed. Not only are 

 the same crystalline forms generally apparent on each cabinet specimen, 

 but even entire veins seem to be productive principally of the same 

 varieties. In the tin-stone of Polgooth near St. Austle, I have r-arely 

 seen any other than minute ciystals of the form of fig. QQ^ PI. 18. 

 That produced by Pednandrae, an extensive tin mine close by the 

 town of Redruth, is almost uniformly of the made described by 

 fig. 208. PI. 25. From Fluel Fanny mine, which produced tin 

 only in the shallow part of the copper vein,* I have never observed 

 any other forms than those described by figs. 108. PI. 20. and 160. 

 and 162. PI. 22. and many of the crystals figured in the series of 

 the 7th and 9th modifications, have, I believe, only been brought 

 from Relistian mine. If it should hereafter more generally appear 



* Pryce, Min. Corn. p. GS. 



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