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 Name	County	Lat	Long	Township	Range	Section
129 Rows	Data exported from DRC 2.0 (c) 2009 Gary Kindel
ADDIE CONSOLIDATED	OWYHEE	43.0125	-116.726111	005 S	003 W	05
ALTA PROPERTY	OWYHEE	43.020278	-116.828611	005 S	004 W	05
ALTER CREEK MINING CO	OWYHEE	42.897222	-116.601667	006 S	001 W	15
BANNER	OWYHEE	43.009167	-116.757222	005 S	004 W	12
BAY STATE GROUP	OWYHEE	42.754444	-116.930833	008 S	005 W	04
BERG	OWYHEE	43.1525	-116.820556	003 S	004 W	21
BERGH-SUNNYSIDE GROUP	OWYHEE	43.075278	-116.718056	004 S	003 W	17
BIG BOY PROSPECT	OWYHEE	42.950556	-116.799167	005 S	004 W	34
BLACK JACK	OWYHEE	43.022222	-116.757222	005 S	004 W	01
BOONEVILLE	OWYHEE	43.0225	-116.755278	005 S	004 W	01
BOULDER CREEK MINES	OWYHEE	42.901389	-116.703889	006 S	003 W	28
BRECCIA ZONE SILVER OCCURRENCE	OWYHEE	43.058889	-116.894444	004 S	005 W	23
BROWNEY	OWYHEE	43.075278	-116.718056	004 S	003 W	17
BRUNZELL	OWYHEE	43.016389	-116.763611	005 S	004 W	01
CHATAUQUA	OWYHEE	43.016389	-116.7525	005 S	004 W	05
CHUCKER HILL	OWYHEE	43.138611	-116.395	003 S	001 E	31
CONSOLIDATED MINE & DREDGE CO	OWYHEE	43.075278	-116.718056	004 S	003 W	17
CONTINENTAL QUICKSILVER	OWYHEE	43.015833	-116.814167	005 S	004 W	04
COOK GROUP	OWYHEE	43.013611	-116.791667	005 S	004 W	03
COPPER KING PROSPECT	OWYHEE	42.708056	-116.983611	008 S	006 W	24
COSMOPOLITAN	OWYHEE	43.089722	-116.709444	004 S	003 W	08
CRESCENT MINE	OWYHEE	42.928889	-116.768611	006 S	004 W	02
CROWN POINT	OWYHEE	43.014444	-116.743889	005 S	003 W	06
CUMBERLAND	OWYHEE	43.002778	-116.686667	005 S	003 W	09
DAISY CLAIM	OWYHEE	43.01	-116.840556	005 S	004 W	05
DAVIS SILVER MINES INC	OWYHEE	42.959444	-116.795	005 S	004 W	27
DELAMAR SILVER MINE	OWYHEE	43.013611	-116.826944	005 S	004 W	05
DELAMAR SILVER MINE AND MILL	OWYHEE	42.999444	-116.696667	005 S	003 W	09
DEWEY	OWYHEE	43.038333	-116.764722	004 S	004 W	36
DOUGH BOY	OWYHEE	42.932778	-116.786944	006 S	004 W	03
EAST CREEK MINE	OWYHEE	42.924444	-116.750833	006 S	004 W	01
EAST FORK OF REYNOLDS CREEK	OWYHEE	43.084722	-116.758333	004 S	004 W	12
EDDY-CONWAY-EDDY MINING & MILLING	OWYHEE	42.547222	-116.1	010 S	003 E	16
EMPIRE	OWYHEE	43.005556	-116.709444	005 S	003 W	08
EMPIRE STATE	OWYHEE	43.021111	-116.753333	005 S	004 W	01
ERDMAN TUNNEL	OWYHEE	43.005556	-116.751667	005 S	004 W	12
GALE EXPLORATION & MINING CORP	OWYHEE	43.075278	-116.718056	004 S	003 W	17
GARFIELD	OWYHEE	43.021111	-116.844722	005 S	004 W	05
GOLD BUG	OWYHEE	43.000833	-116.711389	005 S	003 W	08
GOLDEN CHARIOT	OWYHEE	43.006944	-116.6975	005 S	003 W	09
GOLDEN CROWN MINE	OWYHEE	42.853333	-116.440278	006 S	001 W	34
GOLDEN CYCLE	OWYHEE	43.0175	-116.849722	005 S	004 W	06
GOLDEN GATE	OWYHEE	43.075278	-116.718056	004 S	003 W	17
GOLDEN REWARD MINING & MILLING CO	OWYHEE	42.818611	-116.630278	007 S	003 W	13
GOLDSIL MINES INC	OWYHEE	43.075278	-116.718056	004 S	003 W	17
GRAY EAGLE CLAIM MINE	OWYHEE	42.930833	-116.768333	006 S	004 W	02
HAPPY BOY	OWYHEE	42.547222	-116.1	010 S	003 E	16
HENRIETTA	OWYHEE	43.012778	-116.851667	005 S	004 W	06
HOME CLAIM	OWYHEE	43.075278	-116.718056	004 S	003 W	17
HOMESTAKE	OWYHEE	43.013333	-116.573889	005 S	002 W	04
HOOSIER LEASING	OWYHEE	43.075278	-116.718056	004 S	003 W	17
HOPE CLAIMS	OWYHEE	42.730278	-115.314444	008 S	010 E	17
HORNET	OWYHEE	42.935	-116.787222	006 S	004 W	02
HUMBOLDT	OWYHEE	43.025278	-116.756667	004 S	004 W	36
IDA BELLE	OWYHEE	43.174722	-116.804722	003 S	004 W	10
IDA ELMORE	OWYHEE	43.0075	-116.6975	005 S	003 W	09
INDEPENDENCE SHAFT	OWYHEE	42.750556	-116.940278	008 S	005 W	04
INDIAN HOT SPRING	OWYHEE	42.3375	-115.65	012 S	007 E	33
INTERSTATE GOLD MINING CO	OWYHEE	43.075278	-116.718056	004 S	003 W	17
IVA GRACE	OWYHEE	42.919444	-116.777778	006 S	004 W	11
JEFFERSON CLAIM	OWYHEE	42.938889	-116.789444	005 S	004 W	34
JORDAN CREEK PLACER MINE	OWYHEE	42.978889	-116.878056	005 S	005 W	24
LAST CHANCE PROSPECT	OWYHEE	42.881389	-116.593333	006 S	002 W	20
LEE MINES	OWYHEE	43.013333	-116.573889	005 S	002 W	04
LEPLEY	OWYHEE	43.011667	-116.837778	005 S	004 W	05
LIBERTY	OWYHEE	43.011111	-116.707222	005 S	003 W	04
LINDY	OWYHEE	43.075278	-116.718056	004 S	003 W	17
MAHOGANY	OWYHEE	43.002778	-116.686944	005 S	003 W	09
MAMMOTH MINE	OWYHEE	42.873611	-116.720278	006 S	003 W	29
MANHATTAN	OWYHEE	43.017222	-116.833333	005 S	004 W	05
MARTIN PROSPECT	OWYHEE	42.944167	-116.800556	005 S	004 W	34
MAY DAY	OWYHEE	42.844444	-116.340278	007 S	001 E	04
MCCALL MINE	OWYHEE	42.9075	-116.6525	006 S	003 W	14
MILESTONE	OWYHEE	43.029167	-116.861111	004 S	004 E	31
MINNESOTA	OWYHEE	43.004444	-116.6975	005 S	003 W	09
MONARCA	OWYHEE	43.143611	-116.826667	003 S	004 W	21
MORNING STAR	OWYHEE	43.020556	-116.730278	005 S	003 W	06
MOTHER LODE GOLD MINING & MILLING	OWYHEE	43.075278	-116.718056	004 S	003 W	17
MOUNTAIN CHIEF	OWYHEE	43.013333	-116.573889	005 S	003 W	09
NELLIE ANN NO 1	OWYHEE	42.9475	-116.796389	005 S	004 W	34
NEVER SWEAT	OWYHEE	42.991944	-116.710278	005 S	003 W	17
NORTH AMERICAN SILVER CORP	OWYHEE	43.075278	-116.718056	004 S	003 W	17
NUGENT ANTIMONY MINE	OWYHEE	43.069444	-116.728889	004 S	003 W	18
ONTARIO	OWYHEE	43.018056	-116.773333	005 S	004 W	01
ORO FINO	OWYHEE	43.010833	-116.698333	005 S	003 W	04
OROGRANDE GOLD INC	OWYHEE	43.013333	-116.573889	005 S	002 W	04
OWYHEE SILVER MINING	OWYHEE	42.998889	-116.109167	005 S	003 E	09
PAUPER	OWYHEE	43.001111	-116.710833	005 S	003 W	08
PAUPER	OWYHEE	43	-116.708611	005 S	003 W	08
PERSVERANCE	OWYHEE	42.920556	-116.778333	006 S	004 W	11
PIXLEY BASIN MINING CO	OWYHEE	42.818611	-116.630278	007 S	003 W	13
POORMAN	OWYHEE	43.005556	-116.709722	005 S	003 W	08
POTOSI	OWYHEE	43.014444	-116.732222	005 S	003 W	06
PYRAMID PLACER MINE	OWYHEE	42.986389	-116.086111	005 S	003 E	15
QUEEN OF THE MOUNTAINS	OWYHEE	42.750556	-116.930278	008 S	005 W	09
RICH GULCH MINE	OWYHEE	43.011111	-116.778056	005 S	004 W	02
RISING STAR	OWYHEE	42.919722	-116.776667	006 S	004 W	11
RUBY CITY MINING CO	OWYHEE	43.075278	-116.718056	004 S	003 W	17
RUTH	OWYHEE	43.0175	-116.715556	005 S	003 W	05
SAN JUAN	OWYHEE	43.004444	-116.700278	005 S	003 W	09
SIERRA NEVADA	OWYHEE	43.015278	-116.751389	005 S	004 W	01
SILVER BURG MINE	OWYHEE	43.161389	-116.835833	003 S	004 W	17
SILVER CITY GOLD MINES	OWYHEE	43.075278	-116.718056	004 S	003 W	17
SILVER CORD	OWYHEE	43.005	-116.709444	005 S	003 W	08
SILVER QUEEN	OWYHEE	42.927222	-116.775556	006 S	004 W	02
SILVER VAULT PROPERTY	OWYHEE	43.005833	-116.840278	005 S	004 W	08
SINKER TUNNEL	OWYHEE	43.019722	-116.680833	005 S	003 W	03
SLACKS MOUNTAIN PROSPECT	OWYHEE	43.075	-116.738056	004 S	003 W	18
SOMMERCAMP PLACER	OWYHEE	43.009722	-116.838056	005 S	004 W	05
SOUTH CHARIOT	OWYHEE	43.003333	-116.697222	005 S	003 W	09
SOUTH MOUNTAIN MINE	OWYHEE	42.741667	-116.910278	008 S	005 W	10
STANDARD	OWYHEE	42.740556	-116.904167	008 S	005 W	10
STORMY HILL	OWYHEE	43.004722	-116.706667	005 S	003 W	09
SUMMIT	OWYHEE	43.017778	-116.767778	005 S	004 W	02
SUNNYSIDE MINE	OWYHEE	43.016389	-116.604722	005 S	002 W	05
TAIMAGE RAWHIDE MINE CO	OWYHEE	42.818611	-116.630278	007 S	003 W	13
TANGO	OWYHEE	43.075278	-116.718056	004 S	003 W	17
TENNESSE MOUNTAIN PROSPECTS	OWYHEE	43.050556	-116.785	004 S	004 W	26
TENNESSEE MOUNTAIN PROSPECTS	OWYHEE	43.049722	-116.780833	004 S	004 W	26
TIP TOP	OWYHEE	43.0175	-116.773056	005 S	004 W	01
TRADE DOLLAR	OWYHEE	43.009167	-116.743056	005 S	003 W	07
TREASURE VAULT	OWYHEE	42.930278	-116.778333	006 S	004 W	02
TROOK	OWYHEE	43.013333	-116.716111	005 S	003 W	05
TUNNEL GROUP	OWYHEE	42.750278	-116.922778	008 S	005 W	04
TWIN PEAK PROSPECTS	OWYHEE	43.086667	-116.856667	004 S	004 W	07
VENUS CLAIM	OWYHEE	43.001667	-116.761667	005 S	004 W	12
VILLAGE BLACKSMITH	OWYHEE	43.075278	-116.718056	004 S	003 W	17
WHITE HORSE	OWYHEE	42.93	-116.835833	006 S	004 W	05
YMIR CONSOLIDATED MINING CO	OWYHEE	43.075278	-116.718056	004 S	003 W	17