the primary influences which have led to the formation of auriferous veins." More will be said regarding the occurrence of mineral in depth under the discussion of permanence of mining with depth.

Sulphides occasionally occur alone in nature, but an occurrence which is by far the more common is where several are associated together. Galena, blende and copper pyrites; iron and arsenical pyrites, etc., are illustrations; all of which are common associates of gold. Iron and copper pyrites are often gold-bearing, while galena and blende are almost universally silver-bearing. The Chilean proverb is literally true which says: "If thou findest copper, thou hast gold."

The auriferous deposits of the Southern States, some in Colorado, according to Whitney, and in many other localities here and abroad lead in depth to copper; while the early silver mines of Butte turned to copper with some gold in depth. The placers of this district had as a source of their gold the silver and copper veins discovered later.

The common minerals of gold and silver and their associated minerals are as follows: Native silver occurs in scales, crystals, wires, and only rarely as float silver or nuggets. It is commonly alloyed with copper and gold, and is practically universally found in silver veins especially at the outcrops. Silver glance or argentite is a sulphide of silver, and contains about 85 per cent of silver. It is a soft mineral, dull in appearance and is readily cut. It is often found in high-grade ores, especially of the western states and territories. Horn silver or cerargyrite, a chloride, contains 75 per cent silver when pure. It is soft, heavy and of several shades of gray with a waxy luster. Owing to the ease with which it is cut it has received the name, horn silver. Although not especially rich yet, because it can be easily milled even though low-grade, it is considered a desirable find. It occurred at Silver Reef, Utah, with a value of only $5 to $10 per ton, and was profitably worked. In the West it occurs largely in the outcrops of silver veins, but has been found at depths of 300 to 500 feet, when it usually changes into other silver minerals. The mineral embolite is very similar to cerargyrite except it is green. Pyrolusite or ruby silver is a compound of arsenic, sulphur and silver and carries over 60 per cent of silver. It occurred in the famous Granite Mountain mine, Montana; in the Comstock lode; and in high-grade silver ores of various parts of the

1 Min. and Sci. Press, Vol. 13, p. 50.

West. Brittle silver or stephanite is black, being a compound of antimony, silver and sulphur. In its occurrence, value and characteristics it resembles dark ruby silver.

Practically all gold ores, especially the brittle tellurides, carry more or less silver, which is, however, usually considered as a biproduct.

The various minerals of the base metals such as lead, copper, iron, zinc, and antimony are often silver-bearing. However, these minerals may carry gold and silver in one locality while in a district not far distant with conditions similar or but little different one or the other or both may be wanting. Many of the minerals of lead are argentiferous, the most important ones being the sulphide, carbonate and sulphate.

Gray copper, tetrahedrite, is usually a silver carrying mineral in silver regions, often running as high as 2000 ounces per ton, and is considered one of the most valuable of the silver-bearing minerals. It is quite common in the West. Yellow copper or chalcopyrite is seldom found without traces of silver, which can also be said of blende. Pyrite also carries silver in silver districts, while the other iron minerals seldom carry large amounts, noticeably marcasite also a sulphide.

Silver is almost universally distributed among all forms and kinds of ore-deposits, being even more universal in its occurrence than gold.

The bulk of the gold mined is in the free state, usually found in a gangue of quartz, calcite, siderite, fluorite and barite; the last mentioned being a rare occurrence, and the amount of gold present very small. Gold is found in barite at Big Bend Mountain, Butte County, California, in the Pinkstown ledge.1

Gold also occurs naturally in combination with the rare metals as tellurium and selenium, the former with silver forming sylvanite, and petzite. Sylvanite is the most characteristic, and was named after the place in which it was discovered, the gold field of Transylvania. It is a double telluride carrying both gold and silver, and having an average composition of 28 per cent gold, 16 per cent silver, and 56 per cent tellurium. It is called "graphic tellurium " from its system of crystallization and is a brilliant silvery-white mineral. Pure telluride of gold, calaverite, contains no silver, and has a composition of 44.5 per cent gold and 55.5 per cent tellurium. It was first found in the Stanislaus mine, Calaveras County, Cal1 Min. and Sci. Press, Vol. 70, p. 344.

ifornia, and was named after the county; calaverite and pyrite bear a close resemblance, but can be distinguished between by trial with a knife, the calaverite being easily cut. Probably the best specimens of calaverite found in the Cripple Creek district if not the United States come from the Work mine.1

General beliefs, which may be designated as superstitions, are often held by prospectors, miners and many other persons, and have, to a much larger extent than is supposed, been responsible for many failures to discover ore-bodies and so delayed the development of districts. In the case of prospectors and miners, their ideas as to the occurrence of minerals and their association with rocks is usually a matter of personal experience, which for well-known districts is one of the best possible guides, but when an attempt is made to apply such information to other districts without due consideration of changed conditions and environments, most serious and illogical conclusions are almost sure to result. Again, much information regarding how to locate and trace mineral veins is handed down from one generation to another of practical miners and so constitutes the traditions of various districts and camps; and it may be said that taken as a whole, with respect to mining and milling practice, it is fairly reliable, but there are exceptions to be made, and to illustrate, a number of fallacious sayings and typical misconceptions are given herewith:

1. Local prejudice for and against certain formations- the Butte miner thinks granite an excellent foundation in general; the Cripple Creek miner prefers phonolite to prospect in; the discovery at Ragged Top, Black Hills, has raised "arrowhead flint" in the estimation of many practical miners; since the silver mines of Calico, California, were discovered, masses of pea-green breccia are diligently searched for as the abiding place of chloride; the California miner looks with favor on black slate and greenstone; the Leadville miners find pleasure in a contact of limestone and porphyry; the miners of Homestake want broad zones of quartz and schists, preferring those stained red by iron; in Silver Reef, Utah, there is nothing quite as favorable as white sandstone and drab clay shales, which there carry highgrade silver ores; the Comstock lode miner expected to find values in bonanzas only and for a formation prefers porphyry (propylite), found in the Comstock country.

2. Prejudice against the so-called "specimen " mines, or mines in which show specimens can be obtained.

1 Inst. Min. and Metallurgy, Vol. 8, p. 73.

3. Prejudice in favor of certain strikes which involve numerous and elaborate systems of zones as the 9-, 10-, 11- and 12-o'clock

zones.

4. Prejudice against veins of certain dips, especially those of slight dips, also bedded deposits.

5. Predilection for the so-called "true fissure

"' veins.

6. The appearance of an ore as indicative of its value.1

7. The idea that values always increase with depth, which being true in certain cases cannot be stated as a definite and established rule for all veins, as has been thoroughly demonstrated (?) in the mines of the United States.2

8. Preference to certain slopes of hill or mountain side, as in some districts the northern slope, in other the southern.

9. Choice of low ground, as a depression, which for certain localities may be a sensible thing to do while in others, not. Where veins have outcrops, composed of softer material than the country-rock its more rapid disintegration may result in a sink or depression which may become a surface or underground water-way.

Erroneous statements regarding the occurrence of minerals and their associations are not, however, confined to unwritten sayings, but there is much of a similar character that has been written, and as has been aptly said: "Some put forth a suggestion, it may be the sheerest piece of guesswork; but it finds its way into print, floats with the current literature of the subject, and by virtue of iteration becomes accepted as fact without perhaps ever having been seriously scrutinized." Therefore not only is the practical miner, but also the mining geologist, hampered by prejudices, which have become established and thus have all the weight of precedents. The notion that a theory can be first formulated and then substantiated by facts is changing the natural sequence of things, and is obviously placing the cart before the horse.

In the following pages brief but more or less detailed descriptions of the ore-deposits of the various states and districts are given, although no attempt has been made to give an exhaustive account of all the districts, but rather to discuss the more important and typical mines. However, the material for such a discussion must of necessity be derived largely from the literature on the subject, which in many cases is far from complete and accurate, while in

1 Eng. and Min. Jour., Vol. 37, p. 465, and Min. and Sci. Press, Vol. 78, p. 265. ❜ Colliery Engineer, Vol. 11, p. 246, and U. S. G. S., 4th Ann. Rept., p. 259. 3 Eng. and Min. Jour., Vol. 37, p. 465.

other cases is several years old. Further, unimportant districts. may be given apparently undue prominence, but have in this connection been chosen to illustrate some peculiarity of structure or occurrence which seemed to warrant recording.

In this discussion the states and territories are taken up in alphabetical order while the mines are grouped in districts, which are in a general way arranged in order of prominence.

Occurrence in Veins, by States and Territories.

Alabama. The gold fields of Alabama have been divided into two belts, the north and south; the veins of Chilton, Coosa, Tallapoosa and Chambers counties are embraced in the southern belt, while Clay, Cleburne, Randolph and Talladega form the northern belt.1

There are four classes of ore in the schists as follows: first, micaceous; second, graphitic; third, manganiferous; and fourth, garnetiferous. The garnetiferous ore is probably of the most importance, being a decomposed gneissoid-schist filled with large garnets. In color it is a deep red. The decomposed garnets are goldbearing, the cracks being filled with red ochre which is rich in gold.2 According to one of the latest geological maps of Alabama, the gold-bearing rocks are distinguished as follows: first, the semicrystalline Talladega shales of Algonkian age, including argillaceous and hard, greenish, sandy shales (often graphitic); second, the crystalline schists of Archæan age, including mica-schists, which on the one hand, grade through gneisses into granite, and on the other, into siliceous schists; garnetiferous hornblende-schists, probably of dioritic origin, also occur. The prevailing strike and dip are northeast and southeast respectively.3

The quartz-veins are parallel with the schistosity of the rocks coinciding exactly in both dip and strike. The vein-content is composed of quartz and other gangue minerals usually accompanying gold. Pockets of quartz rich in gold are of quite common occurrence, in which are found grains of crystallized gold ranging in size from wheat grains to cherry stones. Their extreme irregularity both in strike and dip renders their exploitation expensive.

These irregular and lenticular "stringers" have been called "linked veins " by Dr. Becker.

' Eng. and Min. Jour., Vol. 55, p. 486, Bulletins Nos. 3 and 5 Geological Survey of Alabama, and the Mineral Resources of Alabama, 1904, p. 53.

' Federated Inst. Min. Engrs., Vol. 14, p. 96.

3 T. A. I. M. E., Vol. 25, p. 678.