Nevada Nugget Hunters

rehab · Joined: 15 Aug 2006 Posts: 939 Location: NEVADA

PAGE 186 EMJ JUNE 1922

Prospecting in the Yukon and Kuskokwim Regions Near Proximity to Smaller Masses of Granite Considered Favorable for Lode Deposits— Understanding of Geologic Conditions Helpful to the Placer Miner

IN a recent bulletin (789-D) of the U. S. Geological Survey, E R Mertie, Jr., discusses lode prospecting in the Yukon and Kuskokwim regions of Alaska. The following extracts have been taken from the bulletin in question and are interesting:

Lode Prospecting
Most lode prospectors will search mainly for deposits of native gold and for high-grade sulphide ores that also contain gold and silver. It is apparent that such prospecting should be done in and around bodies of granitic rocks, more particularly near the smaller bodies. Valuable ore deposits have seldom been found in interior Alaska in association with granitic masses larger than three or four miles in diameter, and most of those known are associated with much smaller masses or with dikes and sills.
Granitic masses are relatively resistant to erosion and are therefore likely to stand out conspicuously among the other rocks of the region. Exception to this rule are known, however, as for instance on Candle Creek, in the McGrath district, where a body of quartz monzonite lies in the valley of Candle Creek and the surrounding ridges and spurs are composed mainly of basaltic rocks. In the Kuskokwint basin, however, the granitic intrusives are commonly surrounded or adjoined by bodies of basic igneous rocks, some intrusive and some extrusive. The presence of basic rocks in this part of Alaska is therefore an indication that granitic rocks may also be present.
Dikes and sills are also important to locate, for they have been the source of some valuable ores. The Innoko district is one example of the importance of dikes and small intrusive bodies as metallizing agents, and the Parks quicksilver lode, on Kuskokwim river, is another, Such smaller intrusive bodies are difficult to find, because of their inconspicuousness and lack of topographic expression. They. may occur close to larger bodies of granitic rocks, and their presence may sometimes be inferred from this fact Some dikes, however, are offshoots from underlying larger bodies of igneous rock that do not crop out Only diligent prospecting will reveal the location of such dikes.
On geologic maps made by the Geological Survey the positions of the larger masses of granitic rocks are shown.
Sometimes, however, especially in reconnaissance geologic mapping, smaller granitic masses are overlooked, and it is probable that a large proportion of the existing dikes and sills are not seen on a linear traverse. As it is these smaller intrusive masses and dikes that are likely to have originated ore deposits, reconnaissance geologic maps should be taken as general guides rather than infallible indicators of metallization, or the lack of it.
Alter a small intrusive body of granitic rock is found it still remains to be determined whether the intrusion has given rise to any metalliferous deposits. Not all intrusive bodies nor even all small intrusive bodies of granitic rocks have effected metallization, but, on the other band, no valuable ore deposits have been found in interior Alaska that were not connected in some way with such rocks. They are therefore the most favorable places for prospecting, but they are by no means certain to yield commercial ores. Two general methods of prospecting can be recommended. In the Kuskokwim region, where ore deposits are closely associated with the granitic rocks, the prospector should confine his work to these rocks and their immediate margins. 11 no signs of metallization are found in a narrow zone close to the main granitic mass, further search might be made for dikes and other inconspicuous intrusive bodies in the near vicinity before turning to a new area. In the upper Yukon, Tanana, Koyukuk, and Chandalar valleys, however, where ores of the early and intermediate periods are more abundant, the prospector should search for a considerable distance from a granitic body, looking particularly for quartz veins, before he decides that this particular granitic intrusive has not produced any ore deposits. The search in these regions is really a search for quartz veins as such, the position of granitic masses serving only as a general indicator of areas that may be favorable prospecting ground.
It happens more often in Alaska that lode prospecting fellows the development of some gold-placer district Coin-menial placers have not usually been transported any great distance from their bedrock source; and if the lodes that have produced the placers are also of commercial value they are usually located sooner or Later by considering the position and direction of the paystreaks and by laborious prospecting.

Knowledge of the character of the metallization In a region, however, will often be of great value in deducing and locating the bedrock source of the placer deposit. Short cuts that result from an understanding of conditions are certainly worthwhile.

Prospecting for Placers
The prospector of interior Alaska will continue to search for stream and bench placers of gold, for these are the only types of placer deposits, both as to metal content and as to origin, that warrant exploitation at present. All that has been said of lode prospecting applies equally well to placer prospecting, for the lode antedates the placer. It is a great waste of time and effort to prospect blindly from year to year, as many prospectors do, without having any good reason for believing beforehand that a gold placer may exist where they undertake to prospect. Some rich placers have been found in this fly, but It is equally true that an understanding of geologic conditions has often resulted in discoveries that otherwise might not have been made for a long time. The discovery of the high-bench ancient beach placers at Nome is a case In point, for it was predicted by Federal geologists and other examples might be cited in interior Alaska, where men who have been guided by geologic knowledge, either their own or that gained from others, have been able to precede the uninitiated in making important discoveries.
In searching for placers the prospector should hunt first for areas of granitic rocks that give evidence of having been metallized, just as in lode prospecting, and then after the occurrence of metallization has been established he should prospect the streams leading from such areas. One difference, however, must be cited. It is not necessary to find a high degree of metallization or to discover a rich lode before beginning placer prospecting, for a lode deposit of very low grade may by long-continued erosion and stream concentration develop into a high-grad~ placer. The placers of the Klondike region are an example of this condition. In fact, if the prospector finds a small area of granitic rocks or an area cut by many quartz veins or granitic dikes, he would do well to prospect the streams draining such an area, even if evidence of metallization had not been discovered in the bedrock If a commercial gold placer is present in the vicinity, some inkling of the fact is rather likely to be obtained by panning on the bars and ripples of some of the streams that are in the near vicinity.
Another point that deserves stress is the desirability of searching In particular for bench deposits. The conditions that make for the development of continuous commercial pay-streaks are long-continued and deep residual weathering, moderate stream gradients, and a nice adjustment between the factors that regulate the erosion and transportation of rock debris. It is believed that favorable conditions of this sort prevailed more generally In interior Alaska during the 1hysiographic cycle just preceding the present one than they do now. For this reason where bench and stream placers both occur the former are likely to be the richer. The placers of the Fairbanks and Tolovana districts prove the correctness of this hypothesis. Bench placers, of course, are harder and more costly to prospect, because the gold in them is usually buried beneath a great thickness of muck and gravel. The discovery of a paystreak in the present creek channel may perhaps be a logical preliminary step, but when this is accomplished, a thorough search for bench gravels should be made. The original discoverers of placer gold on Livengood creek did not profit in fullest measure by their discovery, because they overlooked the possibility of a higher channel, and the rich bench placers fell into the hands of later arrivals in the camp.
Last of all, some consideration should be given to the physiographic type of country in which workable placers are most likely to be developed. One of the conditions that is regarded as favorable for the accumulation of commercial placers Is a moderate stream gradient; and such gradients are prevalent in the lower parts of the country. To be sure, moderate gradients may be fond in the lower courses of larger streams, even in a district of high relief, but the chances for the formation of a workable placer are less in a wide valley drained by a large stream than in the smaller tributary valleys. It does not necessarily follow from these considerations that workable placers, however, are much better in the regions of low relief if the conditions for bedrock metallization appear to be equally favorable. With few exceptions the rich placer camps of interior Alaska have been found at an elevation of less than 1,000 feet. The Koyukuk camp is an important exception to this rule, but even in this rugged country the principle has its application, for the rich. est placers occur on the lower parts of the tributaries close to the middle, south, and north forks of Koyukuk river and to Bettles, Wild, and John rivers—all large streams. The gradients of the parts of the streams that contain the placers are therefore the lowest that the country affords.

Gold Derived from Intermediate Rocks

Although the gold and the valuable sulphide ores in interior Alaska are all derived originally from the granitic rocks, yet some gold placers have a proximate source of different character. Although the gold contained in the belt of conglomerate that stretches westward from Eagle to Woodchopper creek, in the Yukon-Tanana region, came originally from granitic rocks, yet for the prospector of today this conglomerate may be considered a bedrock source of the gold. Not all the placer gold in this belt, however, comes from this conglomerate, for without doubt some is derived directly from the older rocks, but the importance of the conglomerate as a contributing source of gold should not be overlooked. This example is given to illustrate a principle rather than to indicate that this particular area is of any great importance as a placer field.

Another example of a proximate source of placer gold, other than the original bedrock source, is afforded by the glacial gravels and debris. Mention has already been made of the possibility at some localities of working such deposits. More commonly, however, the original glacial deposits have been reworked by the present streams, which have concentrated the gold and developed workable stream placers. Practically nothing can be said that 3vill aid the prospector either in finding the original paystreaks in the glacial gravels or in finding the stream placers derived from them. Fortunately placers of this type are rare in interior Alaska, being confined largely to the slopes of the Alaska range.

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The deepest rotary-drilled oil wells are in California, according to the U. S. Bureau of Mines. The Standard Oil Co. drilled a test well, Packard No. 11, in Kern county, to a depth of 6,240 ft. A well was drilled in the Kettieman Hills, Kings county, to 6,602 ft. Rotary tools were used from the surface to 3,500 ft., cable tools from 3,500 to 4,070 ft., and rotary tools from 4,070 to 6,602 ft. It is common practice to drill holes with rotary tools in California to depths greater than 4,000 ft. The Producers Oil Co., in the Humble Pool, Texas, drilled a hole with rotary to 5,410 ft. The drill entered rock salt at 2,342 ft., and was still salt when drilling stopped. The depth of salt drilled was, therefore, 3,068 ft. Three other deep test wells drilled in Texas, all with rotary machinery, are those in S. M. Swenson & Sons, at Spur, Dickens county, 4,489 ft.; C. C. Codman, et al., near Vidor, Orange county, 4,640 ft.; and Gulf Production Co., at Spindletop, 4,270 ft.

PACIFIC MINING NEWS or THE ENGINEERING & MINING JOURNAL-PRESS

rehab · Joined: 15 Aug 2006 Posts: 939 Location: NEVADA

Engineering and Mining Journal — Vol.126, No.5 8 4 1928

Mine Production in Alaska In 1927

MINES in Alaska produced $14,404,000 worth of all minerals in 1927, against $17,657,800 in 1926, according to a recent announcement by the U. S. Geological Survey. the total value of the mineral output of the territory since 1880 is $585,374,000.

Of the decrease the most notable was in the quantity and value of the copper produced, but there was also a considerable decrease in the output of gold and in certain of the substances, notably platinum metals, that have been included in the table as miscellaneous mineral products. The decrease in quantity of silver produced reflects in large measure the decrease in copper mining, as much of the silver is recovered from that source. That there was not an even greater decrease is due to the increased production of silver from the silver-lead ores, especially those of the Hyder District of southeastern Alaska. There was increased production of coal, lead, and tin in 1927; in fact, the quantity of lead was the greatest that has ever been produced in any one year, and the quantity of coal was exceeded in only one year since mining began in the territory, and then by not more than 15,000 tons.

The decrease in production of minerals from Alaska, the U. S. interior Department believes, is attributable not to permanent waning of the mining industry but to a number of causes, some of which were purely local, others regional, and still others widespread, affecting not only Alaska but the United States as well. One of the widespread causes was the low price at which metals sold during 1927. This not only had the effect of cutting down the value of the product sold, but also had an even greater effect in curbing production. Obviously, during a period of low prices it is only the part of wise management to reduce the output and await more favorable markets. This condition was especially reflected in the output of copper during the year.

Decrease in gold output is, according to this announcement, of course, not attributable to this cause. Instead, it was caused solely by the decrease in production from the gold placers, for the amount of gold recovered from the lodes increased somewhat. The explanation of the decrease in placer-gold production lies largely in the adverse climatic conditions that prevailed at almost all the placer camps throughout the territory during the season. The winter of 1926-27 had a very light snowfall, so that the runoff from the snow when it melted, furnished unusually little water.

Coupled with this, the early part of the open season was unusually dry, so that at many camps water for mining was not available until August, and by that time many operators had become discouraged and closed up their plants for the season. Even at the large camps the shortage of water forced curtailment of work, so that some of them were operating at only half their normal rate. In many of the districts the season opened so late that seasonal frost lasted even until August. To round out the tale of difficulties, winter set in unusually early in many of the districts, and so further curtailed the amount of mining that could be done.

About equal amounts of gold were derived from lodes and from placers. The bulk of the lode gold still continues to come from mines in southeastern Alaska, and they are increasing rather than diminishing their output. in addition, these mines are already yielding large quantities of silver and lead, and plans are under way for recovering zinc from the ores of the largest mine.

The placer gold was produced fro, a number of camps widely distributed throughout the territory. About 58 per cent of the gold recovered from placer deposits was mined by means of dredges. Twenty-eight dredges were mining in different parts of Alaska, and though mining of this type is generally less affected by adverse climatic conditions, even the largest dredge operators were so hampered in 1927 that they reported a marked falling off in production.

Only one new dredge—that of the American Creek Dredging Company in the Hot Springs district. of the Yukon—was built and began mining during the year. The large dredging enterprise in the Fairbanks district that has been in course of development for several years reached such a stage that late in the year the material for the first two of the fleet of dredges that are to be built was delivered, and the dredges were set up during the winter of 1927-28. The foregoing facts are taken from a report much more in detail on the mineral industry of Alaska in 1927, which is in preparation for publication by the Geological Survey.

The following table shows in summary form the mineral output of the territory for 1927 and, for the sake of comparison, the production of the same minerals in 1926:

rehab · Joined: 15 Aug 2006 Posts: 939 Location: NEVADA

Fairbanks Gold Dredging Active

At Fairbanks, Alaska, Fairbanks Exploration, a subsidiary of U. S Smelting Refining & Mining, is now operating three dredges, one of which was started in July, another in August, and the third in September. The dredges are from 7 to 30 miles distant from Fairbanks, and good roads have been constructed to all three. From 8,000 to 10,000 cu.yd. per day is being handled by the larger dredges from ground thawed by the coldwater method. Five or six other dredges are being operated in the Fairbanks district. The success of these dredges indicates the probability that more will be constructed in the region.

rehab · Joined: 15 Aug 2006 Posts: 939 Location: NEVADA

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LINK TO KETTLE MINE PROPERTY
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rehab · Joined: 15 Aug 2006 Posts: 939 Location: NEVADA

Huge gold nugget found in Alaska
14:52:51 GMT, 23 February, 2007
A mammoth-sized gold nugget has been found in a mine in Alaska by Silverado Gold Mines.

The 13.78 troy ounce gold nugget was discovered in the Mary East underground mine when workers were carrying out some sampling and grade control necessities. Such is the rarity of a nugget this side that it is expected to reach a very high price, especially as it is of jewellery quality.

Large nuggets are a characteristic of Alaskan gold fields and now the tunnels at Mary East are being systematically analysed to give some idea of the gold content being stockpiled within gravel every day.

The "nugget factor" means that gold content throughout the mine is uneven and so Silverado has taken to scanning the walls with a metal detector to give an indication of levels of gold. This also helps to guide the tunnels as they are built.

Some parts of Mary East have been delineated with areas of very rich gold bearing ground including nuggets with a weight of 24.26 ounces.
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rehab · Joined: 15 Aug 2006 Posts: 939 Location: NEVADA

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ALASKA MINING NEWS

General Metals Merger, 1247 Dexter Horton Building, Seattle, Washington, is making provisions to increase its personnel from 6, to 31 individuals. E. A. Gabryel is President; W. J. Galbraith, Forbes Richard, A. H. Dougall, Jr., and Melville G. Henry, Vice-Presidents; and Paul C. Dubuar, Secretary and Treasurer. After the examination of many properties, five were selected and are either conditionally controlled or owned by the merger. They are: the Silver Cord Mine, Point Ashley, Alaska; the Lawrence property in Yavapai County, Arizona; the Alto property in Custer County, Idaho; the Boston American, and the Silver Creek Mines in Snohomish County, Washington; and the Bethania Mines in Mineral County, Nevada.
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