Silver Dyke Mine

Site Name

Primary: Silver Dyke Mine

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Commodity

Primary: Silver
Primary: Lead
Primary: Copper
Secondary: Zinc
Secondary: Gold

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Location

State: Montana
County: Cascade
District: Neihart District

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Land Status

Not available

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Holdings

Not available

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Workings

Type: Surface/Underground

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Ownership

Owner Name: Peter S. Antonioli And Son
Home Office: 1001 West Gold, Butte, Mt 59701

Owner Name: Peter Antonioli And Son

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Production

Year: 1948
Time Period: 1921-1948
Mined: 1059000.000 mt
Material type: ore

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Deposit

Record Type: Site
Operation Category: Past Producer
Deposit Type: Polymetallic veins
Operation Type: Unknown
Year First Production: 1921
Discovery Year: 1875
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: Y
Deposit Size: S

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Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Northern Rocky Mountains
Physiographic Detail: Little Belt Mountains

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Mineral Deposit Model

Model Name: Polymetallic veins

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Orebody

Form: ELLIPTICAL PIPE

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Structure

Type: R
Description: Zone Of Igneous Intrusions Covering Over 800 Square Km

Type: L
Description: Domal Uplift Caused By Intrusion Of Snow Creek Porphyry, Northeast-Trending Fractures And Faults

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Alterations

Alteration Type: L
Alteration Text: Host Rock Highly Altered To Kaolin, Sericite And Quartz.

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Rocks

Name: Diorite
Role: Associated
Age Type: Host Rock
Age Young: Pliocene

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene

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Analytical Data

Not available

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Materials

Ore: Cerussite
Ore: Pyrite
Ore: Malachite
Ore: Galena
Ore: Chalcopyrite
Ore: Sphalerite
Ore: Azurite
Ore: Tetrahedrite
Gangue: Hematite
Gangue: Barite
Gangue: Quartz

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Comments

Comment (Location): UTM COORDINATES OF CENTER OF GLORY HOLE

Comment (Production): AVERAGE METAL RECOVERY ABOUT 75%. OVER 90% OF PRODUCTION BETWEEN 1923 AND 1929. SPORADIC PRODUCTION BY LESSEES SINCE 1929

Comment (Development): MINOR EXPLORATION AND DEVELOPMENT OVER PAST FEW YEARS INCLUDING DRILLING BY VARIUS COMPANIES

Comment (Reserve-Resource): RESOURCES MAY BE EXPECTED IN TWO AREAS: (1) BENEATH THE OPEN PIT AND (2) IN THE REMAINING BRECCIA. MINE WAS PROBABLY CLOSED MORE BECAUSE OF DECLINING METAL PRICES IN 1929-1930 RATHER THAN BECAUSE OF EXHAUSTION OF MINERALIZED GROUND. ABOUT 2,500,000 ST OF BRECCIA WAS EXTRACTED AND ABOUT 2,000,000 ST REMAINS ABOVE ADIT LEVEL. A LARGE AMOUNT OF LOW-GRADE ROCK PROBABLY LIES BENEATH ADIT LEVEL WHICH COULD BE EXTRACTED FROM AN ADIT DRIVEN FROM SQUAW CREEK, POSSIBLY ALONG THE SAVAGE VEIN. AN ADIT AT 6400 FT. WOULD GIVE ACCESS TO AN ESTIMATED 3,000,000 ST MINERALIZED ROCK, ASSUMING AN ORE BODY SHAPED LIKE A VERTICAL INVERTED CONE WITH THE APEX AT AN ELEVATION OF 6400 FT. ABOUT HALF THIS TOTAL, OR 3,000,000 ST MIGHT BE EXPECTED TO CARRY ABOUT 2 TOZ/ST AG.

Comment (Workings): DEPOSIT DEVELOPED BY A COMBINATION OF OPEN CUTS WITH SURFACE DRILLING AND BLASTING AND SHRINKAGE STOPES FROM BENEATH. ORE WAS DROPPED DOWN CHUTES TO ADIT LEVEL AND TRAMMED TO THE MILL. GLORY HOLE AND OPEN CUTS 6,864? LEVEL HAS OVER 3,000 FT OF DRIFTS AND CROSSCUTS; AN UPPER LEVEL AT 7,040? HAD 2,800 FT OF DRIFTS AND CROSSCUTS (THIS LEVEL OBLITERATED BY OPEN PIT); ALSO SOME INTERMEDIATE DRIFTS. (CROWLEY, 1970)

Comment (Geology): PRECAMBRIAN ROCKS ARE PRE-BELT. SNOW CREEK PORPHYRY ALSO CALLED NEIHART PORPHYRY AND CARPENTER CREEK PLUTON BUT CARPENTER CREEK PLUTON IS POOR NAME BECAUSE OF CONFUSION WITH CARPENTER CREEK PORPHYRY

Comment (Deposit): GRAVITY DATA INDICATE A PLUTON OF SNOW CREEK PORPHYRY UNDERLIES SILVER DYKE MINE AND EXTENDS AS MUCH AS 5 KM TO THE NORTHEAST WITH A WIDTH OF ABOUT 3 KM. LACK OF STRONG FAULTS PASSING THROUGH BRECCIA AND LARGE AMOUNT OF LOCALIZED HYDROTHERMAL ALTERATION INDICATES THAT THE BRECCIA PIPE IS A DIATREME.

Comment (Commodity): ORE MINERALS OCCUR IN SMALL VEINLETS AND SMALL CLUSTERS BETWEEN BRECCIA FRAGMENTS AND TO A SLIGHT EXTENT IN FINE-GRAINED DISSEMINATION THROUGH THE ROCK.

Comment (Deposit): Discovery Year: LATE 1800'S

Comment (Development): 1922-23 - 500-TON CONCENTRATING MILL CONSTRUCTED BY STEARNS AND ROGERS (ROBERTSON, 1951). 1923 - AMERICAN ZINC, LEAD, AND SMELTING COMPANY ACQUIRES THE PROPERTY. 1926 - MILL CAPACITY INCREASED TO 950-TON PER DAY. 1929 - BLOCKED OUT ORE DEPLETED. 1947 - SILVER DYKE MINING COMPANY DISSOLVED APRIL 8, 1947 (SUBSIDARY OF THE AMERICAN ZINC, LEAD, AND SMELTING COMPANY). 1951 - PROPERTY OWNED BY H.L. MAURY AND A.G. SHONE OF BUTTE. 1966 - FREEPORT SULFUR COMPANY CONDUCTED A GEOLOGICAL EXPLORATION PROGRAM. 1970 - ANACONDA COMPANY DRILL PROJECT AT THE SILVER DYKE. 1967-1983 - LISTED AS `DEVELOPING? IN MBMG FILES 1984 - TO PRESENT - INACTIVE MINOR EXPLORATION AND DEVELOPMENT OVER PAST FEW YEARS INCLUDING DRILLING BY VARIOUS COMPANIES

Comment (Deposit): MINERALS OCCURRED AS DISSEMINATIONS IN A BRECCIATED MASS OF QUARTZ PORPHYRY, GRANITE PORPHYRY, AND GNEISS.? (ROBERTSON, 1951). ?ORE WAS A COMPLEX MIXTURE OF BOTH SULFIDE AND OXIDE OR CARBONATE MINERALS DISSEMINATED IN A GANGUE OF HIGHLY ALTERRED QUARTZ PORPHYRY AND GNEISS.? (ROBERTSON, 1951). RATIO OF LEAD TO SILVER IS 1 PERCENT LEAD TO 3 OR LESS OUNCES SILVER (CROWLEY, 1970) ?QUARTZ, BARITE, AND THE PRIMARY SULFIDES HAVE BEEN DEPOSITED AS BRECCIA FILLINGS SURROUNDING ALTERED FRAGMENTS OF QUARTZ PORPHYRY, QUARTZ LATITE PORPHYRY, AND GNEISSES. THE BREECCIA FILLINGS TAKE THE FORM OF DRUZY CRUSTS BETWEEN ROCK FRAGMENTS. MINERALIZATION IS NOT PRESENT AS DISSEMINATIONS WITHIN ROCK TYPES EXCEPT FOR PYRITE IN AMPHIBOLITE GNEISSES, AND FOR MINOR DISSEMINATED MOLYBDENITE IN FRAGMENTS OF SNOW CREEK PORPHYRY AT THE EAST SIDE OF THE BRECCIA.? (CROWLEY, 1970)

Comment (Geology): ?THE ORIGIN OF THE ORE HAS NOT BEEN DEFINITELY DETERMINED. IT IS POSSIBLE THAT BRECCIATION OCCURRED WHEN THE CARPENTER CREEK PORPHYRY WAS INJECTED INTO THE MORE BRITTLE SNOW CREEK PORPHYRY. SOLUTIONS CONTAINING THE ORE MINERALS PENETRATED INTO THE BRECCIA AND WERE DEPOSITED IRREGULARLY. THE NEARBY WHIPOORWILL AND SAVAGE VEINS MAY HAVE BEEN THE FEEDER CHANNELS THROUGH WHICH THE MINERAL-BEARING SOLUTIONS CIRCULATED.? (ROBERTSON, 1951) ?MINERALIZATION ... CONTROLLED BY THE BRITTLENESS OF THE COUNTRY ROCK AND TO SOME DEGREE BY THE HYDROTHERMAL ALTERATION WHICH AFFECTED THE INTERSTITAL POROSITY AND PERMEABILITY BETWEEN BRECCIA FRAGMENTS? (CROWLEY, 1970)

Comment (Geology): ?THE BRECCIA PIPE AT THE SILVER DYKE IS IN AN ELBOW OF A QUARTZ LATITE DIKE. THE ELBOW IS THE RESULT OF A CHANGE IN STRIKE FROM EAST-WEST TO SLIGHTLY EAST OF NORTH. A SMALL, NORTHWEST-STRIKING QUARTZ PORPHYRY HAS BEEN EMPLACED AT THE ELBOW. A BRECCIA PIPE WITH A DIAMETER OF ABOUT 500 FEET EMBRACES MOST OF THE QUARTZ PORPHYRY, THE NORTHERN EDGE OF THE QUARTZ LATITE, AND A ROUGHLY CIRCULAR AREA OF GNEISSES NORTH OF THE JUNCTION OF THE TWO PORPHYRIES.? (CROWLEY, 1970)

Comment (Production): PRODUCTION FROM 1921 TO 1948 WAS: 1,167,125 TONS OF ORE FROM WHICH 1,736.67 OZ AU, 3,177,068 OZ AG, 7,453,527 LBS CU, 16,367 LBS PB, AND 8,428 LBS ZN WAS RECOVERED (ROBERTSON, 1951) AVERAGE GRADE FOR THE MILLION TONS OF ORE MINED IN THE 1920?S WAS 1.5% PB, 0.75% CU, AND 5 OZ AG (CROWLEY, 1971)

Comment (Deposit): ELLIPTICAL DEPOSIT WAS 600 FEET LONG BY 400 FEET WIDE AND MINED TO A DEPTH OF 150 FEET (ROBERTSON, 1951)

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References

Reference (General): YOUNG, G.J., 1927, NOVEL MINING AND MILLING METHODS AT THE SILVER DYKE PROPERTY AT NEIHART, MONTANA: ENGINEERING AND MINING JOURNAL V. 123, NO. 6, P. 236-241, FEB. 5, 1927.

Reference (Geology): WEED, W.H., 1900, THE GEOLOGY OF THE LITTLE BELT MOOUNTAINS, MONTANA: U.S. GEOLOGICAL SURVEY TWENTIETH ANNUAL REPORT, PART 3.

Reference (Production): ROBERTSON, 1951, Mines and Mineral Deposits (except fuels), Cascade County, Montana: U.S. Bureau of Mines, Information Circular 7589

Reference (Deposit): SCHAFER, P. A., 1935, GEOLOGY AND ORE DEPOSITS OF THE NEIHART MINING DISTRICT, CASCADE COUNTY, MONT: MONT. BUREAU OF MINES GEOL., MEM. 13, 62 P.

Reference (Deposit): ROBERTSON, A. F., 1951, MINES AND MINERAL DEPOSITS (EXCEPT FUELS), CASCADE COUNTY, MONT: U.S. BUREAU OF MINES INF. CIRC. 7589, 76 P.

Reference (Deposit): MARVIN, R. F., AND OTHERS, 1973, RADIOMETRIC AGES OF INTRUSIVE ROCKS IN THE LITTLE BELT MOUNTAINS, MONT: GEOL. SOC. AM. BULL. VOL. 84, NO. 6 P. 1977-1986.

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Principal Gold Districts of Montana

In Montana, 54 mining districts have each have produced more than 10,000 ounces of gold. The largest producers are Butte, Helena, Marysville, and Virginia City, each having produced more than one million ounces. Twenty seven other districts are each credited with between 100,000 and one million ounces of gold production. Read more: Principal Gold Districts of Montana.