QUICKSILVER.

Otago Witness, Issue 1189, 12 September 1874, Page 6

QUICKSILVER.

Mr. Theodore Raiding, mining engineer, San Francisco, writes to the Aita on this subject, as follows : — "As the quicksilver interest of California has assumed a very important place among the many valuable mines of California, 1 will give you a few items in regard to this metal that may be of some interest to your readers. Twenty years' experience among the. quicksilver mines of this ooast has taught me that two distinct principles are involved in forming the vein, or deposit of this metal. The first, or true lode or vein, consists of a number of minerals which have been molten together and show a vitrous or glassy appearance, and vary aocording to locality. These veins can be readily detected on account of the hydro-carbon, or petroleum, which they absorbed, and still retain, while forcing their way through the siratas containing the hydro-carbon, With this class of veins, gold, silver, copper, antimony, zinc, iron, and sulphur are found, and the black sulphide of quicksilver, as well as the red ore known as cinnabar. The quicksilver is found in chimneys or masses, and is richest below water level. The second formation of quicksilver is caused by the vein matter of the first not penetrating the overlying stratas, but allowing the volatile metals to charge the overlying stratas. Such vein matter may then consist of quartz, quartzite, serpentine, shale, fossiliferous clay slate, soda formations, and sulphur deposits. Only the red ore is found in this class of mines, and no hydro-carbon.

"Nearly all the quicksilver mines, or deposits, have lost more or less metal near the surface, either by fire or by leaching. This leaching has occurred most extensively where iron and sulphur were in excess, and what remains of the original vein is the oxide of iron and the mineral matter of the vein, and it is known as ochre. There is no rule in regard to the wall or country rock of a quicksilver mine. Serpentine, sandstone, pipeclay, talcose slate, and porphyry foriV isuch walls or casing.

" The proper way to prove a quicksilver mine, is either trace up float ore or find the metal in the vein or outcrop. The paying percentage of the ore will entirely depend on the cost of mining and ftiel ; but one-per-cent. ore, will pay handsomely in California, as it costs less to extract quicksilver from its ore than any other metal, and, in regard to the commercial value thereof, there is every reason to be* lieve that- it will be worth more in ten. years than it is at present."