342 Mr. William Phillips on the Oxyd of Tin 



some years ago, under the name of pea tin, perhaps from their 

 size. They have evidently been rounded by attrition, and appear 

 to be a species of wood tin from the variation in colour on the 

 surface, which is generally of a hair-brown. 



There is in my collection, a specimen, which I took from the 

 heaps of tin on Poldice mine, that is of remarkable character. 

 The general mass is of a light brown colour ; minute veins of 

 different shades of brown and black tin alternate in bands in the 

 same direction. It is compact and hard, but not brittle, and gives 

 sparks with a steel j its fracture is uneven. It may be well sup- 

 posed from its great weight, to consist almost wholly of the oxyd 

 of tin. It is accompanied by the black oxyd on one side, and 

 very minute veins, apparently of quartz, traverse it in various 

 directions. 



Alluvial depositions of tin of considerable extent and depth have 

 been found in several parts of Cornwall, which it is believed, is the 

 only part of Europe in which tin occurs under these circumstances. 

 The grains of it, which it may be presumed, are for the most part 

 crystals rounded by attrition, are mostly very small, and sometimes 

 exhibit marks of crystallization, generally of the made. Stream 

 tin affords from 65 to 15 per cent, of the purest grain tin. Its 

 freedom from arsenic perhaps arises from the ore collected in the 

 stream works being detached portions of the pure oxyd. And its 

 presence in the regulus of tin procured from the ore of the veins 

 may be supposed to arise from its being frequently accompanied 

 by arsenicated iron. It is somewhat remarkable that the only 

 traces of gold to be found in Cornwall, are in the stream works, 

 in which it sometimes occurs in small grains, mostly detached, but 

 occasionally accompanied by quartz. A few years ago, a specimen 

 of considerable size was discovered, I believe in Carnan stream 



