50 APPENDIX. 



Mr. Heuland, in 1823, exhibited to the Geological Society of 

 London {Transactions, Second Series 1, p. 119) a diamond in 

 Cascalho surrounded by scorodite (a cupreous arseniate of iron), 

 which I do not see in M. Damour's lists, but which was found 

 by Eschwege ; and Dana says it encrusts quartz and beryl, and 

 is found in Victoria with gold and arseno-pyrites. Of the latter 

 mineral Mr. TJlrich gives three localities. It has not yet been 

 found on the Cudgegong. But Schorl rock does occur there, 

 and in the sands of Bahia, at Diamantina, in Minas Greraes ; and 

 this mineral, there called Feijao, as well as hydrophosphate of 

 alumina, is considered an indication of diamond. 



It is stated by Mawe (Travels in Brazil) that the mines of 

 Cerro-do-Trio annually produced, between 1801 and 1806, to the 

 amount of from 20,000 to 25,000 carats, and that the weight of 

 those sent to the Treasury in Rio Janeiro was 115,675 carats. 



As an encouragement to diamond seekers in this Colony may be 

 mentioned that numbers of the Brazilian crystals are so small 

 that four or five make only a grain, so that it takes sometimes 

 seventeen to twenty to weigh a carat. There are rarely in the 

 course of the year more than two or three of the latter weight, 

 and it takes two years to find one of 30 carats ; so that when a 

 negro workman found one of 17^ carats, called an octavo, he was 

 crowned with flowers, conducted in triumph to the manager, fresh 

 clad, and set at liberty. This is reported by Malte Brun {Precis 

 III. p. 293). Dr. Thompson has ascertained that up to 12th 

 January, 1870, 9-lOths of the diamonds at the Two-mile Flat 

 weighed less than a carat, and that 497 together weighed 120 

 carats ; but as they were different in size, the average is assumed 

 at one carat each, the largest being If carat. One, however, 

 had been found weighing 5| carats. 



These facts are interesting as correlating, so far as is known, 

 the prospects of this Colony and those of Brazil. 



To prevent reference to it hereafter, I may mention now that a 

 new and valuable work on precious stones (" Sandhuch der 

 I^delsteiii") was published in Vienna last year by Dr. Albrecht 

 Schrauf. I find a notice of it in the Quarterly Journal of Science, for 

 January, 1870. In it is given a formula for calculating the value 

 of diamonds, which tested by the price actually paid for the Sancy 

 stone (£20,000), taking the weight at 53 carats, and the price of 

 the first carat at £15, and which is near to the theoretical result 

 (£21,862 10s. Od.), appears to be tolerably correct. It is this : — 

 m 



— («i + 2) « = value, 

 2 

 where m is the number of carats, and a the value of one. 



I have already noticed some of the facts stated by Messrs. 

 Heusser and Claraz. 



