With the exception of the gold from Houseman Creek, the range in true fineness of gold from Lightning Creek and its tributary creeks is remarkably small. Gold of highest fineness, 915 parts per thousand, is from Donovan Creek, and at successive points up-stream the gold is progressively but slightly less fine until Butcher Bench is reached, where the true fineness is 905. At Dunbar Flat and Houseman Creek the fine- ness is considerably less. The decrease in fineness up-stream is more apparent in the -bullion fineness figures and was evidently known by the early miners and gold-buyers. The prices paid by the banks at Barkerville before they closed in 1879 for Lightning Creek gold was $17.55 per ounce for gold mined down-stream from Spruce Canyon and only $17 per ounce for gold mined up-stream from Spruce Canyon.* These are the net prices paid in Barkerville after deducting bank commission, express, insurance, assay, and Mint charges.

The reason for this variation is not known. However, it is believed to reflect a regional variation in the gold fineness, and is not interpreted as suggesting that the gold has migrated down-stream from the head of the creek and with differential solution of its silver content has been correspondingly enriched in gold.

The range in fineness of Slough Creek placer gold is small. There is an exact correspondence of the true fineness of the placer gold from the two parts of the Slough Creek benches; i.e., that from the Ketch and that from the Point Company and other Chinese workings between Nelson and Devils Lake Creeks. Gold of lowest fineness, 921, is from Coulter Creek; that of highest fineness, 937, from Leo Bedford’s hydraulic on Devils Lake Creek, and 936 from a single 71l-oz. shipment from the Slough Creek benches west of Devils Lake Creek. There does not appear to be any definite pattern of variation of the fineness in the Slough Creek section. It should be noted that gold of 923 average true fineness was recovered by E. Rask at the very summit of Devils Lake and Chisholm Creeks, whereas placer gold south of the divide is of lower fineness. This placer gold is close in fineness to that of surface lode gold (927) from the Acme group (see Table II), some 7,500 feet to the south-west.

The true fineness of placer gold from Slough Creek and its tributaries is con- siderably higher than that of gold from the Lightning Creek section. The average of Lightning Creek gold might be considered as 910 fine or slightly less, whereas the average fineness of Slough Creek gold is 930 or slightly more. This appears to be a fundamental regional difference between the placer golds from the two sides of the divide. Its full interpretation is not possible because of the lack of information regard- ing lode-gold fineness in the Slough Creek section and because of the lack of specific information concerning the problem of variations of gold fineness in general.

The fineness of Lightning Creek gold is comparable to the highest gold fineness obtained from samples from Burns Mountain veins. That the fineness of the placer gold is higher than that of the low fineness gold of sample 5 in Table II is not incon- sistent with the fact that under certain circumstances primary lode gold may be enriched and produce placer gold of considerably higher quality (Mertie, 1936, pp. 234-236).

RELATION OF PLACER DEPOSITS TO BEDROCK GEOLOGY.

The most significant feature of the Stanley area is that a very high percentage of the placer gold produced has come from the stretches of Lightning Creek and of the Slough Creek benches bounded on the west by the Last Chance-Nelson Creek fault and on the east by the Burns Creek-Butcher Bench fault. Moreover, the productive tributary creeks, with few minor exceptions, lie entirely within or very close to the area limited to east and west by these two faults. Van Winkle, Last Chance, Burns, and Nelson Creeks were the richest tributaries, and all lie along or exceedingly close to these two faults. In contrast, Grub Gulch, Perkins, Devils Lake, and Coulter

* Minister of Mines, B.C., Ann. Rept., 1902, p. 104. 40