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Friday, March 26, 2010

Silver Mines of Southwestern Idaho

From   The principles of economic geology  By William Harvey Emmons  (page 248)

Gold-silver-adularia Veins.—The gold-silver veins of De Lamar and Silver City, Idaho, are post-Miocene deposits that were formed very near the present surface. These veins are in rhyolite, basalt, and granite. The surface at the time of deposition, as shown by Lindgren,2 was not more than 700 to 2,000 feet above the deposits mined. The gangue consists of quartz and adularia, with some chalcedony. Much of the quartz is pseudomorphous after calcite or barite. Small quantities of chlorite, epidote, barite, siderite, and calcite are present also. The ore minerals are gold, silver, argentite, proustite, pyrargyrite, polybasite, miargyrite (AgSbS2), chalcopyrite, zinc blende, galena, pyrite, and a little marcasite. Some of the rich ore was formed very near the old surface and is probably primary. The analyses of the altered rhyolite show that potash and aluminum have been removed as well as soda. The removal of both the alkalies, the presence of marcasite and chalcedony, and the extensive kaolinization of the walls are noteworthy.

Chloritic Alteration in Granitic Rock.—In many metalliferous districts three principal types of alteration are recognized— chloritic alteration in a zone extending far out from the deposits, extensive sericitization within this zone, and silication near the master fractures. Where the fractures are closely spaced the area of sericitic alteration may be hundreds of feet wide and the chloritic alteration may extend over thousands of feet. At Butte, Mont., the chloritic alteration consists chiefly of the development of chlorite and pyrite in the iron-bearing minerals, and the clouding of feldspar by incipient sericitization. Some epidote and secondary quartz also are developed. This phase appears in practically all the granite within the mineral-bearing area at Butte. Alteration of this type is attended by relatively little addition or subtraction of material. It is believed to have been brought about by gases or by waters that deposited ore and sericitized the wall rock near the ore-bearing fissures. Although less extensive, the chemical changes brought about by chloritic alteration are chemically similar to those accomplished by sericitization.

Chloritic Alteration in Lavas (Propylitic Alteration).—In many districts, particularly in certain western camps, where ore deposits were formed in lavas during Miocene and Pliocene time, the country rock is altered over wide areas. Near the surface, rooks fracture more readily than at greater depths, because they are not held down by so great a mass of overlying rocks. Hot waters and gases ascending along major fractures spread out, entering cracks and joints and mineralizing practically the entire country rock between the veins. In such a district the rocks in an area of more than a square mile may be altered, and if the district lies in a mountain range the mineralized area may be noted by an observer miles away. Experienced prospectors appreciate the significance of the alterations, which give what some designate a "kindly look" to the rock. Andesite and basalt are generally changed to a dull green; rhyolite to a paler green and locally to a chalky white.

A common type of such alteration is the propylitic phase, in which the following changes are noteworthy: Minerals containing iron, such as hornblende, pyroxene, and biotite, are altered to chlorite, epidote, and pyrite. Glassy feldspars lose their glassy habit. A glassy groundmass is recrystallized largely to feldspar and quartz, with some chlorite, epidote, and calcite. Some sericite is nearly always developed. Chemically there is a loss of sodium and generally of alkaline earths; sulphur and water are added. These changes are very common in andesites, dacites, andjmsalts. In rhyolite less chlorite and more sericite may be formed, and quartz may be added in considerable quantities by the silication of iron-bearing minerals and feldspars. In many districts the alteration increases near the veins, where less chlorite is developed and more sulphides and quartz. As in granite, three types of alteration are distinguished in some districts— chloritic alteration extending over wide areas, sericitic alteration nearer the veins, and silication of the wall rock adjoining the main fractures.

Sericitic and Propylitic Alteration Compared.—Sericitic alteration and propylitic alteration are the most common types of hydrothermal metamorphism of igneous rocks near veins that are formed at moderate and at shallow depths. They are generally attended by similar chemical changes, although the changes involved in sericitization are greater.

The propylitic and sericitic alterations at Tonopah, Nevada, have been closely studied. The Tonopah district,3 is a fault mosaic of Tertiary eruptive rocks, probably of Miocene and Pliocene age.
Mine NameCountyLatLongTownshipRangeSection
129 RowsData exported from DRC 2.0 (c) 2009 Gary Kindel
ADDIE CONSOLIDATEDOWYHEE43.0125-116.726111005 S003 W05
ALTA PROPERTYOWYHEE43.020278-116.828611005 S004 W05
ALTER CREEK MINING COOWYHEE42.897222-116.601667006 S001 W15
BANNEROWYHEE43.009167-116.757222005 S004 W12
BAY STATE GROUPOWYHEE42.754444-116.930833008 S005 W04
BERGOWYHEE43.1525-116.820556003 S004 W21
BERGH-SUNNYSIDE GROUPOWYHEE43.075278-116.718056004 S003 W17
BIG BOY PROSPECTOWYHEE42.950556-116.799167005 S004 W34
BLACK JACKOWYHEE43.022222-116.757222005 S004 W01
BOONEVILLEOWYHEE43.0225-116.755278005 S004 W01
BOULDER CREEK MINESOWYHEE42.901389-116.703889006 S003 W28
BRECCIA ZONE SILVER OCCURRENCEOWYHEE43.058889-116.894444004 S005 W23
BROWNEYOWYHEE43.075278-116.718056004 S003 W17
BRUNZELLOWYHEE43.016389-116.763611005 S004 W01
CHATAUQUAOWYHEE43.016389-116.7525005 S004 W05
CHUCKER HILLOWYHEE43.138611-116.395003 S001 E31
CONSOLIDATED MINE & DREDGE COOWYHEE43.075278-116.718056004 S003 W17
CONTINENTAL QUICKSILVEROWYHEE43.015833-116.814167005 S004 W04
COOK GROUPOWYHEE43.013611-116.791667005 S004 W03
COPPER KING PROSPECTOWYHEE42.708056-116.983611008 S006 W24
COSMOPOLITANOWYHEE43.089722-116.709444004 S003 W08
CRESCENT MINEOWYHEE42.928889-116.768611006 S004 W02
CROWN POINTOWYHEE43.014444-116.743889005 S003 W06
CUMBERLANDOWYHEE43.002778-116.686667005 S003 W09
DAISY CLAIMOWYHEE43.01-116.840556005 S004 W05
DAVIS SILVER MINES INCOWYHEE42.959444-116.795005 S004 W27
DELAMAR SILVER MINEOWYHEE43.013611-116.826944005 S004 W05
DELAMAR SILVER MINE AND MILLOWYHEE42.999444-116.696667005 S003 W09
DEWEYOWYHEE43.038333-116.764722004 S004 W36
DOUGH BOYOWYHEE42.932778-116.786944006 S004 W03
EAST CREEK MINEOWYHEE42.924444-116.750833006 S004 W01
EAST FORK OF REYNOLDS CREEKOWYHEE43.084722-116.758333004 S004 W12
EDDY-CONWAY-EDDY MINING & MILLINGOWYHEE42.547222-116.1010 S003 E16
EMPIREOWYHEE43.005556-116.709444005 S003 W08
EMPIRE STATEOWYHEE43.021111-116.753333005 S004 W01
ERDMAN TUNNELOWYHEE43.005556-116.751667005 S004 W12
GALE EXPLORATION & MINING CORPOWYHEE43.075278-116.718056004 S003 W17
GARFIELDOWYHEE43.021111-116.844722005 S004 W05
GOLD BUGOWYHEE43.000833-116.711389005 S003 W08
GOLDEN CHARIOTOWYHEE43.006944-116.6975005 S003 W09
GOLDEN CROWN MINEOWYHEE42.853333-116.440278006 S001 W34
GOLDEN CYCLEOWYHEE43.0175-116.849722005 S004 W06
GOLDEN GATEOWYHEE43.075278-116.718056004 S003 W17
GOLDEN REWARD MINING & MILLING COOWYHEE42.818611-116.630278007 S003 W13
GOLDSIL MINES INCOWYHEE43.075278-116.718056004 S003 W17
GRAY EAGLE CLAIM MINEOWYHEE42.930833-116.768333006 S004 W02
HAPPY BOYOWYHEE42.547222-116.1010 S003 E16
HENRIETTAOWYHEE43.012778-116.851667005 S004 W06
HOME CLAIMOWYHEE43.075278-116.718056004 S003 W17
HOMESTAKEOWYHEE43.013333-116.573889005 S002 W04
HOOSIER LEASINGOWYHEE43.075278-116.718056004 S003 W17
HOPE CLAIMSOWYHEE42.730278-115.314444008 S010 E17
HORNETOWYHEE42.935-116.787222006 S004 W02
HUMBOLDTOWYHEE43.025278-116.756667004 S004 W36
IDA BELLEOWYHEE43.174722-116.804722003 S004 W10
IDA ELMOREOWYHEE43.0075-116.6975005 S003 W09
INDEPENDENCE SHAFTOWYHEE42.750556-116.940278008 S005 W04
INDIAN HOT SPRINGOWYHEE42.3375-115.65012 S007 E33
INTERSTATE GOLD MINING COOWYHEE43.075278-116.718056004 S003 W17
IVA GRACEOWYHEE42.919444-116.777778006 S004 W11
JEFFERSON CLAIMOWYHEE42.938889-116.789444005 S004 W34
JORDAN CREEK PLACER MINEOWYHEE42.978889-116.878056005 S005 W24
LAST CHANCE PROSPECTOWYHEE42.881389-116.593333006 S002 W20
LEE MINESOWYHEE43.013333-116.573889005 S002 W04
LEPLEYOWYHEE43.011667-116.837778005 S004 W05
LIBERTYOWYHEE43.011111-116.707222005 S003 W04
LINDYOWYHEE43.075278-116.718056004 S003 W17
MAHOGANYOWYHEE43.002778-116.686944005 S003 W09
MAMMOTH MINEOWYHEE42.873611-116.720278006 S003 W29
MANHATTANOWYHEE43.017222-116.833333005 S004 W05
MARTIN PROSPECTOWYHEE42.944167-116.800556005 S004 W34
MAY DAYOWYHEE42.844444-116.340278007 S001 E04
MCCALL MINEOWYHEE42.9075-116.6525006 S003 W14
MILESTONEOWYHEE43.029167-116.861111004 S004 E31
MINNESOTAOWYHEE43.004444-116.6975005 S003 W09
MONARCAOWYHEE43.143611-116.826667003 S004 W21
MORNING STAROWYHEE43.020556-116.730278005 S003 W06
MOTHER LODE GOLD MINING & MILLINGOWYHEE43.075278-116.718056004 S003 W17
MOUNTAIN CHIEFOWYHEE43.013333-116.573889005 S003 W09
NELLIE ANN NO 1OWYHEE42.9475-116.796389005 S004 W34
NEVER SWEATOWYHEE42.991944-116.710278005 S003 W17
NORTH AMERICAN SILVER CORPOWYHEE43.075278-116.718056004 S003 W17
NUGENT ANTIMONY MINEOWYHEE43.069444-116.728889004 S003 W18
ONTARIOOWYHEE43.018056-116.773333005 S004 W01
ORO FINOOWYHEE43.010833-116.698333005 S003 W04
OROGRANDE GOLD INCOWYHEE43.013333-116.573889005 S002 W04
OWYHEE SILVER MININGOWYHEE42.998889-116.109167005 S003 E09
PAUPEROWYHEE43.001111-116.710833005 S003 W08
PAUPEROWYHEE43-116.708611005 S003 W08
PERSVERANCEOWYHEE42.920556-116.778333006 S004 W11
PIXLEY BASIN MINING COOWYHEE42.818611-116.630278007 S003 W13
POORMANOWYHEE43.005556-116.709722005 S003 W08
POTOSIOWYHEE43.014444-116.732222005 S003 W06
PYRAMID PLACER MINEOWYHEE42.986389-116.086111005 S003 E15
QUEEN OF THE MOUNTAINSOWYHEE42.750556-116.930278008 S005 W09
RICH GULCH MINEOWYHEE43.011111-116.778056005 S004 W02
RISING STAROWYHEE42.919722-116.776667006 S004 W11
RUBY CITY MINING COOWYHEE43.075278-116.718056004 S003 W17
RUTHOWYHEE43.0175-116.715556005 S003 W05
SAN JUANOWYHEE43.004444-116.700278005 S003 W09
SIERRA NEVADAOWYHEE43.015278-116.751389005 S004 W01
SILVER BURG MINEOWYHEE43.161389-116.835833003 S004 W17
SILVER CITY GOLD MINESOWYHEE43.075278-116.718056004 S003 W17
SILVER CORDOWYHEE43.005-116.709444005 S003 W08
SILVER QUEENOWYHEE42.927222-116.775556006 S004 W02
SILVER VAULT PROPERTYOWYHEE43.005833-116.840278005 S004 W08
SINKER TUNNELOWYHEE43.019722-116.680833005 S003 W03
SLACKS MOUNTAIN PROSPECTOWYHEE43.075-116.738056004 S003 W18
SOMMERCAMP PLACEROWYHEE43.009722-116.838056005 S004 W05
SOUTH CHARIOTOWYHEE43.003333-116.697222005 S003 W09
SOUTH MOUNTAIN MINEOWYHEE42.741667-116.910278008 S005 W10
STANDARDOWYHEE42.740556-116.904167008 S005 W10
STORMY HILLOWYHEE43.004722-116.706667005 S003 W09
SUMMITOWYHEE43.017778-116.767778005 S004 W02
SUNNYSIDE MINEOWYHEE43.016389-116.604722005 S002 W05
TAIMAGE RAWHIDE MINE COOWYHEE42.818611-116.630278007 S003 W13
TANGOOWYHEE43.075278-116.718056004 S003 W17
TENNESSE MOUNTAIN PROSPECTSOWYHEE43.050556-116.785004 S004 W26
TENNESSEE MOUNTAIN PROSPECTSOWYHEE43.049722-116.780833004 S004 W26
TIP TOPOWYHEE43.0175-116.773056005 S004 W01
TRADE DOLLAROWYHEE43.009167-116.743056005 S003 W07
TREASURE VAULTOWYHEE42.930278-116.778333006 S004 W02
TROOKOWYHEE43.013333-116.716111005 S003 W05
TUNNEL GROUPOWYHEE42.750278-116.922778008 S005 W04
TWIN PEAK PROSPECTSOWYHEE43.086667-116.856667004 S004 W07
VENUS CLAIMOWYHEE43.001667-116.761667005 S004 W12
VILLAGE BLACKSMITHOWYHEE43.075278-116.718056004 S003 W17
WHITE HORSEOWYHEE42.93-116.835833006 S004 W05
YMIR CONSOLIDATED MINING COOWYHEE43.075278-116.718056004 S003 W17

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