﻿British Mineralogy. 323 



It has long been known, however, that the alluvial deposits in 

 the beds of many of the Cornish rivers contain native gold in the 

 form of nuggets and small rounded or flattened grains or scales ; 

 and it appears not improbable that the gold forming the orna- 

 ments of prehistoric origin frequently found in Cornwall and 

 the neighbouring counties may have been derived from this source. 

 A nugget of gold from these alluvial deposits in the collection of 

 the late Sir Charles Lemon weighs more than one ounce, and 

 the largest nugget recorded is stated to have weighed 2 ozs. 

 3 dwts. ; but these are quite exceptional instances, as in general 

 the weight of the particles does not exceed a few grains. 



Most frequently the gold is found associated with the so-called 

 stream-tin (cassiterite or oxide of tin) ; and when the stream- 

 works were,as anciently, an important source of the tin-production 

 of Cornwall, a not inconsiderable quantity of native gold seems 

 to have been obtained during the washing of the alluvial deposits 

 for tin ore. As these deposits have now been nearly, if not alto- 

 gether, exhausted, it has become extremely difficult to meet with 

 authentic specimens of Cornish gold at the present time. 



In the British Museum may be seen a specimen of stream-tin 

 ore with gold from the Carnon stieam-works; and Messrs. Greg 

 and Lettsom mention gold being found at the Crow Hill stream- 

 works at Trewarda, Kenwyn, at Llanlivery near Lostwithiel, and 

 at Laddock near Grampound. 



As no analysis of native gold from Cornwall is to be met with 

 in any of the works of mineralogy which I have examined, I 

 have for several years been endeavouring to secure an authentic 

 specimen for the purpose of determining its chemical composi- 

 tion, but only succeeded last month, when Mr. W. J. Henwood, 

 F.R.S., kindly sent me a specimen, obtained through Mr. Pe- 

 therwick of St. Austell, from St. Austell Moor. 



The gold thus obtained was of a rather deep gold-colour, but 

 of a dingy lustre, the surface of the particles being worn and 

 rounded by attrition ; it consisted of nine minute nuggets of very 

 irregular forms, the largest of which weighed 2*1 grains, whilst 

 their aggregate weight was only 5 - 46 grains. 



The specific gravity, determined upon the entire quantity at 

 disposal, was found to be 16*52 at 60° Fahr. ; and the chemical 

 analysis gave the following numbers as the percentage composi- 

 tion of the gold itself: — 



Gold 90-12 



Silver 9-05 



Silica with sesquioxide of iron . . 0*83 



100-00 

 Y2 



