Ch. 2: Gems in Ceylon

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	158	GOLD IN BRAZIL.

	fine gold. The gold was well mixed with the sludge, &c,—quicksilver was then added, and the operation of amalgamating performed in the ordinary manner. The amalgam was treated also in the ordinary manner, and the gold recovered weighed '4786 grains nearly, showing that the loss was 4/28 per cent. The loss may be partly accounted for by the mere handling of the fine gold in a very damp atmosphere, i. e., weighing it, transferring it to the dish of sludge, &c, and re-weighing it. This system however is, when very carefully managed, so certain, that if the actual assay produce of a parcel of quartz was at the rate of one ounce per ton, the gold got by amalgamation would weigh 19 dwts. 3-5 grains. It will be observed that the result in every case must necessarily be slightly in defect, never in excess. Messrs. Johnson and Matthey, the well-known Analytical Chemists, in a report to the Directors of the Port Phillip and Colonial Gold Mining Company, make the following statement :— " We finally had recourse to amalgamation, and were surprised at the ready results so obtained(having been led to suppose that the mineral—pyrites—was unworkable under that process) ****** The results recorded by the Analysts are highly interesting :—



	MINERALS OF THE SAN FRANCISCO VALLEY, BRAZIL. (From the South American Journal, May 12th, 1881.) The following is taken from the report of Col. W. Roberts:— Gold. Almost all the basin, from Piranhas to the heads of the river, is known to be auriferous, and perhaps no region of the wdrld has undergone so many trials as those parts of the basin which belong to Minas Geraes and Goyaz, wherein a great extent of the surface has been literally turned over in quest of the precious metal. To judge by the appearance of the country, and the bad success of many recent attempts, the gold of the region is exhausted. But without being able to form an authoritative opinion, my study of the matter having been too limited, I am far from supposing such to be the case. At least the ill-success of many promising undertakings should not be taken as proofs, inasmuch as many causes co-operated therein and they should be attributed largely to the difficulties of communication, to ignorant and extravagant administration, and to the ruinous speculations which have induced abandonment of the undertakings before the mines had been properly tested. Gold appears in many modes in almost all kinds of rocks in the region, but for mining it is enough to treat of four of the modes, namely: pyritous veins, quartzite ones, beds of ferruginous quartzite known as itabirite, and superficial gravels and sands. The known and worked veins of pyrites are those of Morro Velho, Cuyaba

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