County, produced over $6,000,000 and is about 3 feet wide, and the Sheep Ranch mine, in Calaveras County, which does not exceed 4 feet in width and is usually less than 3 feet, has yielded $3,000,000.1

The Mother lode, one of the large veins in the state, had produced up to 1899 between seventy and one hundred million dollars worth of gold. The Keystone, Old Eureka, Utica, Plymouth, Consolidated and Kennedy, have each yielded from 5 to 12 millions, while several others have recorded productions of from 2 to 3 millions. This lode in Amador County alone has produced from $35,000,000

1 Min. and Sci. Press, Vol. 88, p. 178.

to $50,000,000. The product of the whole lode exclusive of the placers largely derived from it is approximately $100,000,000. For several years prior to 1899 the lode had yielded one-fifth of the annual gold product, while its entire yield lay between one-third and one-fourth the gold obtained by quartz-mining.1

The yield of the placers has been variously estimated — W. H. Pettee estimated the yield of California placers to be 4.75 cents per cubic yard, which was based on the Cement Mining Company's work at North Fork, where 43 million cubic yards of gravel had been washed, yielding 2 million dollars; Laur's estimate was 16 cents, while Prof. Silliman's was 30 cents per cubic yard.

Sixteen years of operating at Sebastopol Hill, by the American Company, shows a yield of 25 to 30 cents per cubic yard, while the entire yield of the gravel lying between the Middle and South Yubas has been estimated at from 30 to 35 cents per cubic yard.2

Averages of figures obtained from different operations, as hydraulic-, drift-, river- and beach-mining gave an approximate estimate of the yield of the various gravels found in the state. An average of thirteen hydraulic operations, in which the value of the gravels ranged from $12 to $822 per ton, gives $152.05 per ton. Four drift mines showed an average of $103.25 per ton, the range being from $15 to $271. Similarly, four river-mining operations gave an average of $14.21 per ton, range $10 to $27 per ton, while ten beach workings gave an average of $6.82, with a range of 80 cents to $18.50 per ton.3 The total yield of California hydraulic mines during 1906 was about $975,000, of which $635,669 has come from Del Norte, Humboldt, Siskiyou and Trinity counties, all of which are drained by the non-navigable streams emptying into the Pacific, and to which the legal restrictions against hydraulic-mining do not apply. The $339,471 remaining is accredited to the counties in the drainage basin. of the Sacramento and San Joaquin rivers, where the Caminetti law is in force, and the Débris Commission has jurisdiction. This gives an idea of the condition of hydraulic-mining in the state at the present time.

The source of the gold and silver product for 1905, as reported from the mines, by kind of ore is given in Table XXV:

1 T. A. I. M. E., Mines and Minerals of California, p. 63.

5

2 Min. and Sci. Press, Vol. 23, p. 24, The Auriferous Gravels of the Sierra Nevada of California, Vol. I, p. 371, and Eng. and Min. Jour., Vol. 11, p. 120. 3 Min. and Sci. Press, Vol. 69, p. 230.

4 Min. and Sci. Press, Vol. 94, p. 53.

U. S. G. S., Mineral Resources, 1905, pp. 122, 123 and 125.

The following table shows the gold and silver product for the period 1848 to 1905.1

1 Table compiled from Reports Director of Mint, Mineral Resources, Mineral Industry, and School of Mines Quarterly, Vol. 3, p. 80.

† From 1850 to 1856 river-mining was an important factor in the production of gold. Hydraulic-mining operations were inaugurated in 1853.

§ The decline noted was due largely to the discovery of the Comstock lode, which detracted the attention from California.

The effect of the State and Federal injunctions against hydraulic-mining in California was to completely close the mines by 1887.

¶ Improvements in methods of mining and milling began to affect the output of gold; not an unimportant factor was dredging. The first modern dredge was built in California in 1897-the revival of placer-mining.

The past few years have shown considerable fluctuation in output of the mines of California, 1905 showing no decline (nor any material increase) in the gold production. The activity in dredging operations was probably responsible for the slight increase.

Nevada County, which includes the Grass Valley district, led, having a yield of over $3,000,000.

There was a falling off in silver production for 1905, owing to the decreased output of siliceous ores in Kern County, also the copper ores in Shasta County. However, from the present outlook in the copper districts a material increase in silver may be expected from that source in the future.1

Canada: Silver Islet Mine. For reasons already given a discussion of the Silver Islet ore-deposit, Ontario, Canada, has been given in connection with each of the subjects considered, and accordingly its production of the precious metals is herewith given.

From the beginning of operations in September, 1870, to the close of navigation, in 1878, 2,174,499.5 ounces refined silver had been obtained, which had a value of $2,921,727.24. Adding to this amount that mined since its discovery and operation by the Montreal Mining Company, a total of $2,948,019.81 was produced by this mine. The total production of the mine when it was abandoned was $3,039,557.49.

The output of the Silver Islet mine from 1868 to the fall of 1871 was as follows:

The silver extracted from the ore mined from 1874 to 1875,

At the commercial price of silver of $1.20 per ounce, the value of this silver amounts to $1,195,718.45.1

The analyses of samples of the Silver Islet ore are given below, each representing an average of about 13 tons:

The Roman numerals indicate classes into which the ore was separated: AI, containing between 2,000 and 4,000 ounces of silver per ton, or 7 to 14 per cent; II, 600 to 2,000 ounces or 2 to 7 per cent; III, above 100 ounces or 0.3428 per cent; and IV, the waste of the mine, averaging 40 ounces, or 0.14 per cent.?

In the fall of 1878 the second bonanza was struck, which is said to have yielded 800,000 ounces of silver.3

Colorado. Although mining began in a more or less desultory way in Colorado shortly after the discovery of gold in California, yet it was not until 1877 that accurate data were collected regarding the output. From 1877 to 1905, inclusive, the gold production amounted to $332,976,047, while the total estimated production from the year 1858 to and including 1905 was $379,776,047. Unlike California, and a number of the Western states, the placers of Colorado were comparatively few, and the values were often quite irregularly distributed. It is not surprising therefore that the production of the early mining days was relatively small- the output from early placer-mining for the period 1858 to 1867 being estimated at $25,000,000 or $30,000,000.

The production of gold during 1877 to 1890 was between $3,000,000 and $4,000,000, being derived principally from the ores of Gilpin, Clear Creek and Boulder counties, and to a certain extent

1 T. A. I. M. E., Vol. 8, pp. 248, 249 and 252, 1880.

2 T. A. I. M. E., Vol. 2, pp. 91 and 92, 1873.

Eng. and Min. Jour, Vol. 34, p. 322.