May Day Mine

The May Day Mine is a silver and gold mine located in La Plata county, Colorado at an elevation of 9,219 feet.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Satelite View

MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.

Site Name

Primary: May Day Mine
Secondary: Patented Claims: Gertrude, MS 16616
Secondary: May Day, MS 16985
Secondary: Golden Rule, MS 16985
Secondary: Gilmore, MS 16985
Secondary: Pat, MS 16985
Secondary: Hesperus, MS 16985
Secondary: Cimarron, MS 16985
Secondary: Kenton, MS 16985
Secondary: Lord Kitchner, MS 17108
Secondary: Sunrise, MS 17124
Secondary: Boston, MS 19078
Secondary: Tunnel, MS 19078
Secondary: Tram, MS 19078
Secondary: Thanksgiving, MS 19078
Secondary: Brooklyn, MS 20171

Commodity

Primary: Silver
Primary: Gold
Secondary: Lead
Tertiary: Copper
Tertiary: Zinc
Tertiary: Mercury
Tertiary: Tellurium
Tertiary: Antimony

Location

State: Colorado
County: La Plata
District: California (La Plata) District

Land Status

Land ownership: National Forest
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.
Administrative Organization: San Juan N. F.

Holdings

Not available

Workings

Not available

Ownership

Owner Name: Farris Mines
Home Office: Grants, N.M.
Years: 1975 -

Production

Not available

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Year First Production: 1903
Year Last Production: 1942
Discovery Year: 1903
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: N
Deposit Size: S

Physiography

General Physiographic Area: Intermontane Plateaus
Physiographic Province: Colorado Plateaus
Physiographic Section: Navajo Section

Mineral Deposit Model

Model Name: Polymetallic veins

Orebody

Not available

Structure

Type: R
Description: San Juan Uplift, Four Corners Platform

Type: L
Description: La Plata Dome, Idaho-Day Fault System

Alterations

Not available

Rocks

Name: Diorite
Role: Associated
Age Type: Host Rock
Age Young: Late Jurassic

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

Name: Diorite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Paleocene

Analytical Data

Analytical Data: ASSAYS FROM CDM ANNUAL OPERATOR REPORTS SHOW CRUDE ORE FROM 1923-1932 TO CONTAIN 0.9 TO 2.5 OZ/TON AU, 6 TO 28 OZ/TON AG, 1 TO 216% ZN. MILLING ORE FROM 1933-1936 CONTAINED 0.14 TO 0.22 OZ/TON AU, 1.2 TO 2.5 OZ/TON AG, AND 3% ZN. CONCENTRATES FROM 1933-1938 CONATINED 4.4 TO 8 OZ/TON AU, 47 TO 75 OZ/TON AG, AND 2.3 TO 4.6% ZN.

Materials

Ore: Sylvanite
Ore: Pyrite
Ore: Cerargyrite
Ore: Krennerite
Ore: Chalcopyrite
Ore: Bromyrite
Ore: Sphalerite
Ore: Galena
Ore: Calaverite
Ore: Petzite
Gangue: Hemimorphite
Gangue: Barite
Gangue: Calcite
Gangue: Quartz
Gangue: Aragonite

Comments

Comment (Workings): MAY DAY MINE DEVELOPED BY NOS. 1, 2, 3, AND 4 TUNNELS; SUNRISE, LAMB, GRIZZLY, AND DERBY TUNNELS; AND BROOKLYN WORKINGS. NO. 1 CROSSCUT TUNNEL DRIVEN N 65 E FOR 750 FT TO MAY DAY VEIN (INTERSECTING MAY DAY FAULT AT 220 FT AND IDAHO FAULT AT 550 FT FROM PORTAL). FROM THIS POINT, EAST WORKINGS INCLUDE DRIFT ON MAY DAY VEIN GENERALLY S 40 E FOR 170 FT TO RAISE AND SPLIT CONNECTING MAY DAY AND IDAHO FAULTS, THENCE N 73 E FOR 880 FT TO BROOKLYN VEIN ON WHICH SHORT DRIFT DRIVEN SE. AT END OF CROSSCUT, DRIFT DRIVEN ON MAY DAY VEIN N 27 W FOR 60 FT TO FISH-HOOK SPLIT, THENCE N 65 W FOR 70 FT ON FISH-HOOK SPLIT (WITH ADDITIONAL DRIFTS 170 FT SE AND 110 FT NW), THENCE GENERALLY N 25 W ALONG MAY DAY VEIN FOR 940 FT, WITH 400-FT BRANCH TUNNEL N 52 E AT 330 FT FROM CROSSCUT AND 70-FT RAISE AT 810 FT FROM CROSSCUT. AT 40 FT NORTH OF FISH-HOOK SPLIT ON MAY DAY DRIFT IS WINZE TO LOWER LEVELS. NO. 2 TUNNEL LOCATED 1030 FT SW OF NO. 1, DRIVEN N 54 E FOR 2100 FT, THENCE S 70 E FOR 1000 FT TO WINZE AND

Comment (Location): (LAND STATUS AND ADMINISTRATIVE AREA LOCATIONS CALCULATED USING GIS OVERLAY ANALYSIS FOR SAN JUAN N. F.). CLAIMS LIE EAST OF LA PLATA RIVER NE FROM MAY DAY TOWNSITE UP LITTLE DEADWOOD GULCH, 3.2 MILES SSW FROM LA PLATA TOWNSITE (UNSURVEYED SECTIONS). ELEV AND LAT-LONG GIVEN ARE FOR PORTAL OF MAY DAY NO. 1 TUNNEL (N2 SW NE SEC. 28). ; INFO FROM LAND.ST :1974

Comment (Commodity): ORE MINERALS LISTED ARE GENERAL OCCURRENCES REPORTED FOR BOTH MAY DAY AND IDAHO MINES

Comment (Deposit): IDAHO FAULT. "810" VEIN, WHICH MAY BE SOUTHWARD EXTENSION OF GERTRUDE FOUND SOUTH OF MAY DAY FAULT, CONTAINED WORKABLE ORE IN AND NEAR PONY EXPRESS LIMESTONE. EASTERNMOST VEIN IS BROOKLYN, LYING BETWEEN IDAHO AND MAY DAY FAULTS. ON NO. 1 LEVEL, MILLABLE ORE STOPED FROM BRECCIATED, KAOLINITIZED PORPHYRY.

Comment (Deposit): COUNTRY ROCKS CONSIST OF SW-DIPPING TRIASSIC AND JURASSIC SEDIMENTARY ROCKS INTRUDED BY DIORITE-MONZONITE PORPHYRY DIKES AND CUT BY EAST-WEST-TRENDING IDAHO-MAY DAY FAULT SYSTEM. MAJOR REVERSE FAULTS OF SYSTEM BELIEVED TO BE PRE-ORE, EXERTING CONTROL OVER EXTENT AND FLOW DIRECTION OF MINERALIZING SOLUTIONS. SERIES OF NORTH-TRENDING, STEEPLY EAST DIPPING NORMAL FAULTS CONTAIN PRINCIPAL VEINS. MAY DAY, MOST PRODUCTIVE VEIN IN MINE AREA, TRENDS N O TO 25 W, DIPS 55 TO 85 NE WITH DISPLACEMENT OF 20 TO 30 FT. VEIN IS KNOWN ONLY NORTH OF MAY DAY FAULT, AND WHAT IS CALLED MAY DAY THAT IS DEVELOPED IN NO. 1 DRIFT AND B LEVEL ARE ACTUALLY WESTERLY SPLITS OF VEIN. VEINS DEVELOPED FARTHER NORTH IN DERBY, GRIZZLY, AND LAMB TUNNELS NOT CONCLUSIVELY SHOWN TO BE MAY DAY PROPER. WALL ROCKS OF PRODUCTIVE VEIN ORE RANGE FROM ENTRADA TO LOWER MORRISON; DEPOSIT ALSO CONTAINS REPLACEMENT ORE IN PONY EXPRESS LIMESTONE. GERTRUDE VEIN LIES BETWEEN IDAHO AND MAY DAY VEINS AND DEFINITELY KNOWN ONLY NORTH OF

Comment (Workings): SHORT BRANCH DRIFTS; MAY DAY FAULT AT 1690 FT FROM PORTAL, MAY DAY VEIN AT 1820 FT WITH 150-FT DRIFT DRIVEN N 6 W; RAISE TO "B" LEVEL AT 90 FT ALONG DRIFT, AND DRIFT DRIVEN S 62 E FOR 170 FT. NO. 3 TUNNEL LOCATED 1280 FT SW OF NO. 1, DRIVEN N 40 E FOR 530 FT TO FACE, INTERSECTING MAY DAY FAULT AT 310 FT AND VALLEY VIEW VEIN AT 470 FT, ON WHICH DRIFT DRIVEN NNW, CONNECTING WHITH IDAHO NO. 1 WORKINGS. NO. 4 TUNNEL LOCATED 1200 FT SW OF NO. 1, DRIVEN N 58 E FOR 370 FT TO FACE, INTERSECTING 545-FT SHAFT AT 320 FT FROM WHICH DRIFT DRIVEN NNW FOR 300 FT AND CONNECTING WITH MAY DAY NO. 3 AND VALLEY VIEW WORKINGS. AT SHAFT INTERSECTION, CROSSCUT DRIVEN GENERALLY EAST FOR 1120 FT TO FACE; AT 1080 FT; BRANCH DRIVEN NORTH FROM WHICH MILLER INCLINE DRIVEN TO 820-FT POINT IN NO. 2 TUNNEL. "A" LEVEL IS 200-FT NORTH-SOUTH- TO SE-TRENDING DRIFT ON MAY DAY VEIN BELOW NO. 1 LEVEL OFF WINZE AT 50 FT NORTH OF FISH-HOOK SPLIT IN NO. 1 TUNNEL. "B" LEVEL ACCESSIBLE FROM RAISE OFF MAY DAY DRIFT IN NO. 2

Comment (Production): COMPLETE PRODUCTION RECORD. NO PRODUCTION REPORTED FOR 1916-1919, 1932, 1937, AND AFTER 1942. DUE TO DISCREPANCIES WITH CDM ANNUAL OPERATOR REPORTS, ANNUAL ORE TONNAGES FOR 1903-1932 COULD BE TOTALS OF CRUDE ORE AND CONCENTRATES PRODUCED FROM MILLING ORE. FIGURES FOR MILLING ORE AND CONCENTRATES FOR 1933-1935, CONCENTRATES FOR 1936 AND 1938, ORE GRADES FOR 1933-1934, AND CONCENTRATE GRADES FOR 1933, 1935-1936, AND 1938 FROM CDM ANNUAL OPERATOR REPTS. AS CRUDE ORE, MILLING ORE, AND CONCENTRATES NOT CONSISTENTLY REPORTED SEPARATELY, CUMULATIVE TOTALS ARE NOT POSSIBLE.

Comment (Development): FOLLOWING DISCOVERY OF VALLEY VIEW VEIN ON IDAHO PROPERTY IN 1902, OUTCROP OF MAY DAY VEIN DISCOVERED IN 1903, FOLLOWED BY INITIAL PRODUCTION THAT SAME YEAR; LARGER SCALE PRODUCTION BEGAN IN 1904. IN 1910 DISPUTE AROSE OVER APEX RIGHTS BETWEEN VALLEY VIEW AND MAY DAY MANAGEMENTS; LITIGATION ENDED IN 1912 WHEN COURT ORDERED TRANSFER OF PART OF VALLEY VIEW'S CLAIMS TO MAY DAY (POSSIBLY THE GERTRUDE AND SUNRISE). UNTIL 1933, ALL ORE EITHER SHIPPED CRUDE OR WASHED AND HAND-SORTED TO SHIPPING GRADE. MINE OPERATED BY MAY DAY GOLD MINING AND MILLING FROM 1903-1922, BY CUMBERLAND MINES CO. FROM 1923-1926, BY MAY DAY DEVELOPMENT CO. FROM 1927-1928, BY MAY DAY GOLD MINING CO. IN 1929, BY HOUSER LEASING CO. FROM 1930-1932, BY MAY DAY MILLING CO. FROM 1933-1940, AND BY ROWE LEASING CO. FROM 1941-1942. EARLY EXPLORATION WAS HAHAZARD, CARRIED OUT WITHOUT PROPER STUDY OF COMPLICATED STRUCTURE. IN EARLY YEARS OF PRODUCTION, MINE MANAGER BELIEVED THAT AS MUCH HIGH-GRADE ORE WAS STOLEN AND CREDITED TO

Comment (Development): OTHER MINES AS WAS PRODUCED FROM FROM MAY DAY. FIRST ATTEMPTS AT MILLING MADE IN 1933 BY MAY DAY MILLING CO. MAY DAY AND IDAHO MINES ACCOUNT FOR OVER HALF OF DISTRICT'S PRODUCTION.

Comment (Workings): LEVEL, CONSISTS OF 630 FT OF DRIFT NW ON MAY DAY VEIN AND 940-FT ENE TUNNEL ALONG IDAHO FAULT TO BROOKLYN VEIN ON WHICH 260-FT DRIFT DRIVEN SE. WORKINGS TO NW: SUNRISE TUNNEL LOCATED 950 FT NE OF NO. 1 PORTAL, DRIVEN GENERALLY NNW FOR ABOUT 360 FT. LAMB TUNNEL LOCATED 1100 FT NORTH OF NO. 1 TUNNEL, DRIVEN N 30 W FOR 150 FT ON MAY DAY VEIN, THENCE N 63 E FOR 50 FT, THENCE GENERALLY N 35 W FOR 330 FT ALONG VEIN TO FACE. GRIZZLY TUNNEL LOCATED 580 FT NW OF LAMB TUNNEL, DRIVEN GENERALLY N 15 W FOR 140 FT TO FACE, WITH INCLINED RAISE AT 85 FT FROM PORTAL TO MAY DAY DRIFT IN DERBY TUNNEL. DERBY TUNNEL LOCATED 1090 FT NW OF LAMB TUNNEL, DRIVEN N 78 E FOR 870 FT TO FACE, WITH 210-FT NNE DRIFT ON GERTRUDE VEIN AT 450 FT FROM PORTAL, 250-FT NNW DRIFT ON MAY DAY VEIN AT 665 FT FROM PORTAL, AND 110-FT SSE DRIFT ON MAY DAY VEIN AT 665 FT FROM PORTAL WITH INCLINED WINZE TO GRIZZLY TUNNEL. BROOKLYN DISCOVERY WORKINGS LOCATED 1850 FT ESE FROM NO. 1 PORTAL AND CONSIST OF TWO SHORT TUNNELS ON BROOKLYN

Comment (Workings): VEIN.

References

Reference (Deposit): ECKEL, E.B., AND OTEHRS, 1949, GEOLOGY AND ORE DEPOSITS OF THE LA PLATA DISTRICT, COLORADO: USGS PROF. PAPER 219, P. 73-76, 143-149, PLS. 25, 26.

Reference (Deposit): MCCAUSLAND, R.D., 1934, REPORT ON THE DAY MINE, LA PLATA COUNTY: UNPUB. ENG. REPT., 20 P.

Reference (Deposit): COLORADO DIV. MINES INF. REPTS. AND ANNUAL OPERATOR REPTS.

Reference (Deposit): BLM MINERAL SURVEYS MS 16616, 16985, 17108, 17124, 19078, 20171

Reference (Production): ECKEL AND OTHERS, 1949, P. 144 (AS COMPILED FROM USGS AND USBM RECORDS); COLORADO DIV. MINES ANNUAL OPERATOR REPTS.

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