Gold.—This metal has been found in the Coast Mountains, from the county San Francisco on the north to Luis Obispo on the south. The slates and serpentine formations which have been previously noticed in this report, are found to be receptacles of gold here as in the Sierra Nevada; the rocks are extensive in the Coast Mountains, often comprising an entire ridge for miles; they are usually flanked by the granite. During the past summer, the placers in the county Santa Cruz were much worked; the gold found there was principally on the San Lorenzo and its tributaries; it was fine, and much resembled that found in the Coyote Hill, near Nevada; under the glass it had all the appearance of having suffered but little from attrition by water, the surface of the grains being rough, as though just detached from their original matrix. The slates and serpentine rocks occur on both sides of this creek, with small veins of quartz running through them; and, from what we know of auriferous districts of this and other countries, the presumption is that gold in situ exists here almost to a certainty.
On the upper portions of the Carmello, in the county of Monterey, gold is also found, in the immediate vicinity of the rancho Tulecita. Farther to the south-east, near the head waters of the creek, it is also found on the tributaries of the main stream that flow from the western ridge of these mountains. On the Francisquito, a tributary of the Carmello, coming from the south-west, and twelve miles from the coast, it is also found near the house of Barondo. Three or four Mexicans were working with the battea at the time I passed that ranche. The serpentine rocks are largely developed on the east flanks of the granite ridges, and from their course they may be considered as forming the northern part of a series which occurs at the Mission San Antonio, fifty miles south.
The district of country in the Coast Mountains in which the auriferous deposits are now known to occur, is about eighty miles in length, and thus far is confined to the counties of Santa Clara, Monterey, and the north part of Luis Obispo. This is a material addition to the already known area in which this metal is found, and its location in what has heretofore been considered the agricultural districts of the State, will in time exert a beneficial influence in the permanent settlement of those sections.
Antimony.—The common sulphuret of this metal is very abundant in the Monte Diablo range; at Mount Oso it is found in large masses, also at various other points throughout these mountains; it occurs in considerable quantities in some parts of the county of Santa Barbara. This mineral is deserving of attention, as it often contains a notable quantity of silver, though as yet no specimens which have been found in this country contain a large per centage of this metal.
Bitumen.—Bituminous springs abound through the Coast Mountains, and in some places is much used in the construction of buildings and walks in front of buildings; for the latter purpose it is admirably adapted in situations where the sun will not have too powerful an effect upon it, as in such cases it is apt to become soft. In the counties of Santa Clara, Santa Cruz, and Monterey, several of these springs occur, and further south, are found more abundant. Information has been received of an extensive deposit of bitumen in Contra Costa, some six miles from the shores of the bay, but at what point I have as yet been unable to learn. This article has been used of late in the manufacture of gas, for illumination, and it possesses some advantages over the common oil or resin gas in general use; a sufficient quantity for the illumination of the country may be easily obtained, and at low rates, when required for this purpose.
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PLACER MINING.
The writer enters into a long treatise on this branch of mining, and represents its progress as being very extensive during the last two years.
It is now ascertained to a certainty that the placer ranges extend to the east, within ten or fifteen miles of the “summit ridge,� so called, of the Sierra Nevada; and the condition in which it is found at these points is similar in all respects to that in the older or more western sections, with, perhaps, one exception, and that the relative age of both. There are evidences which clearly indicate a deposit of gold older than the diluvial drift of the lower or western diggings, (which latter is often confounded with the drift deposits of the tertiary periods in this country,) the character of which differs in almost every respect from any other deposit yet observed in this country, except in this particular range.
Its direction has been traced for about seventy miles, and is found to extend through the counties of Butte, the eastern part of Yuba, Sierra Nevada, Placer and El Dorado; it appears to have an average breadth of about four miles, with an elevation of four thousand feet above the sea for the greatest part of its length.