GEOLOGICAL OCCURRENCE OF GOLD.

55

ceous; through a long series of similar geological events they have the same leading mineralogical characteristics, the world over, whatever their original composition or structure; and it is only in them that auriferous quartz veins are found. The productiveness of this quartz, nearly always the gangue of gold, seems to be in proportion to the thoroughness of the change wrought in the character of the accompanying or country rocks by heat. Where they are but slightly altered from the condition in which they were deposited, they are found to contain only traces of gold. Where, on the contrary, they have been invaded by igneous masses from below, broken, tilted up on their edges, and rendered crystalline in structure by being heated to the fusing point and afterwards allowed to cool, there is reason to expect the presence of gold as it is found in workable lodes. Veins which occur in the eruptive rocks are seldom of much value.

In general the quartz veins may be presumed to have originated at the time of the metamorphic action on the strata themselves; and when there are igneous rocks in the immediate vicinity, the development of the metallic contents of the adjacent veins is usually ascribed to their presence; since it is so often found that the metalliferous deposits are intimately associated with eruptive masses. It does not follow, however, that these phenomena throughout the world were confined to any particular geological epoch. There may have been a repetition of similar conditions at periods very remote from each other. One of the most striking facts devel

oped by Murchison in his great work on Russia is that the impregnation of the rocks of the Ural with gold took place as late as the drift epoch. In the Southern United States no great change appears to have taken place since the epoch of the new red sandstone; and the date of the gold-bearing veins may with probability be placed between that formation and the carboniferous. In Australia the elevation of the auriferous strata and their impregnation with gold seem to have been later than the epoch of the coal. In California it is probable that the auriferous masses are included in slates of paleozoic age, highly metamorphosed; but of the period of the igneous action which may be supposed to have been the cause of their impregnation with gold, little can be predicated with certainty. In the Cordilleras of South America the period of metalliferous emanations seems to have been after the deposition of the cretaceous strata; and disturbances of the rocks which may have been attended with phenomena of this character have evidently continued down to a very recent geological period, both there and in California.

It must be plain to the reader by this time that very little is known as to how or when the lower sedimentary rocks were metamorphosed, the vein fissures made, filled with quartz or other vein-stone; or how or when the quartz or the whole rock strata in which it occurs, as the case may be, was impregnated, as the savans have it, with gold. We at least are most positively ignorant of the whole matter and confess to very little desire of being impreg

MINERALOGICAL OCCURRENCE OF GOLD. 57

nated with a knowledge of it. In the blaze of universal ignorance on the subject the Colorado rocks are likely to fare as well as any other rocks, and meanwhile it is of more interest to us how and when we shall get the gold out than how and when it was put in.

use.

tance.

Gold and platina form an exception in their mode of occurrence to all the other metals in common While silver, tin, copper, lead, zinc, iron, are obtained almost exclusively in the form of ores, that is to say, in combination with a mineralizer, of which the most common one is sulphur, gold is found, all over the world, in the native state, its combination with tellurium, an exceedingly rare substance, being confined to one or two localities, and therefore of no particular economical imporWhat is termed native gold, is an alloynot an atomic union of gold and silver the latter forming from one-half to less than one-hundredth of the mass with traces of iron, copper, and other metals. It is the form in which nearly all the gold in use in the world has been obtained. Gold and iron are almost as intimately associated as gold and silver. There is hardly a specimen of sulphuret of iron (iron pyrites - called ore in the vernacular of Colorado) in which a trace of gold might not be found by sufficiently delicate manipulation. When the iron pyrites has undergone decomposition and become converted into a hydrated oxide, from exposure to the atmosphere or other cause, the gold may often be separated with advantage; but in the attempt to separate gold from

3*

undecomposed iron or copper pyrites, there is a considerable loss in amalgamating; so much so as to almost uniformly prevent, up to the present time, its being profitably done. The efforts perseveringly made by different parties in Colorado to overcome this difficulty will receive attention in a subsequent part of this book.

It is not from workings in the solid rock that the gold of commerce has been chiefly derived, however, or at least not from the workings of man. Nature herself has been in the field for countless ages, separating it from the rock, washing, concentrating, and accumulating it in the superficial de-. tritus lying on the rock in place, and included by geologists in the drift and alluvial deposits. All that man has had to do, is, by various simple, mechanical contrivances, to separate the precious metal-in the form of round, flattened, and (rarely) crystalline particles, varying in weight from mere nothing to thirteen hundred and nineteen ounces from the dirt. This is called "placer mining," and as we have remarked before, is the most ephemeral at the same time that it is the most fascinating pursuit in the world. No doubt the ancients derived their gold from such deposits, but who can now tell where they were? So we are fast arriving at the exhaustion of them in a new world, and the far future will perhaps find it equally hard to point out their locality.

CHAPTER III.

Discoveries of Gold in the Mountains-John H. Gregory and the Gregory Lode-History of Discovery Claim on the Gregory— Placer and Bar Diggings-First Mining Laws-Russell GulchQuartz Mining-Gregory District Organized and Code of Laws Adopted.

VERY early in the year 1859 the citizens of Auraria, in Arapahoe County, Pike's Peak, began to scatter out to hunt for gold. After a pretty thorough prospecting of all the neighboring streams, they settled upon Clear Creek, or the Vasquez Fork of the South Platte, as being the richest. Diggings were opened on that stream, three or four miles from the edge of the Mountains, and a town soon sprang up, called "Arapahoe." At one time there must have been fifty houses in this town; to-day, not one remains on the spot to mark its site. Another town was soon commenced, a little higher up the stream; just where it fairly escapes from the Foot-hills. This was called "Golden City," and in the latter part of the year was built up very rapidly, reaching, during the next Summer, the highest point of prosperity it has yet attained. On Ralston Creek, a small tributary of Clear Creek, diggings were opened and worked with considerable success.