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Esperanza Mine

Occurrence in Guanacaste, Costa Rica with commodities Gold, Silver
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Geologic structures
  12. Ore body information
  13. Controls for ore emplacement
  14. Economic information about the deposit and operations
  15. Mining district
  16. Ownership information
  17. Links to other databases
  18. Bibliographic references
  19. General comments
  20. Reporter information

Geologic information

Identification information

Deposit ID 10007887
MRDS ID CS00121
Record type Site
Current site name Esperanza Mine
Alternate or previous names Esperanza De Libano Mine, Libano Mine, El Libano De Tilaran Mine

Geographic coordinates

Geographic coordinates: -84.98606, 10.41773 (WGS84)

Site location context

Political divisions (FIPS codes)

Guanacaste(province)

Costa Rica(country)

North America(continent)

Land(continent)

Geographic areas

Country State
Costa Rica Guanacaste

Comments on the location information

  • AT LIBANO (LIBANO DE TILARAN). THE THREE MAIN VEINS ALONG FAULTS THAT HAVE BEEN MINED ARE THE AZUL, BLANCA, AND FORTUNA VEINS. OTHER VEINS INCLUDE MARAVILLA NORTE, MARAVILLA SUR, CHIRICUACO, 40, CEIBO, GONGOLA, AND PUNTA LA PLANCHA. THE AZUL VEIN OCCUPIES A N-TRENDING NORMAL FAULT DIPPING STEEPLY TO THE E AND HAS PROVIDED MOST OF THE ORE MINED TO DATE. THE BLANCA VEIN, HIGHLY MINERALIZED WITH AU-BEARING QUARTZ, IS ONE OF THE SPLAYS IN THE HANGING WALL OF THE AZUL FAULT. THE BLANCA VEIN TRENDS S 58 W. THE FORTUNA VEIN OCCUPIES A STEEP S-DIPPING FISSURE STRIKING N 40 E TO N 65 E. IT HAS BEEN EXTENSIVELY MINED ALONG ITS ENTIRE 140 M STRIKE LENGTH. THE SULFIDE MINERALS OCCUR AS DESCRETE LAYERS IN EARLY COCKSCOMB QUARTZ AND AS DISSEMINATIONS IN OTHER STAGES OF QUARTZ.

Commodities

Commodity Importance
Gold Primary
Silver Secondary

Materials information

Materials Type of material
Electrum Ore
Calcite Gangue
Chalcopyrite Gangue
Pyrite Gangue
Quartz Gangue
Sphalerite Gangue

Alteration

  • (Local) Replacement And Veining Of Andesite By Calcite And Epidote; Phenocrysts Replaced By Sericite; Chlorite In Groundmass. Pervasive Silicification.

Mineral occurrence model information

Model code 151
USGS model code 25d
Deposit model name Epithermal vein, Sado
Mark3 model number 28

Host and associated rocks

  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite
    Rock unit name Monteverde;Monteverde;Monteverde
    Rock description Monteverde;Monteverde;Monteverde
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite
    Rock unit name Monteverde;Monteverde
    Rock description Monteverde;Monteverde

Nearby scientific data

(1) -84.98606, 10.41773
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description N- And Ne-Trending Faults

Ore body information

  • General form VEIN

Controls for ore emplacement

  • Changes In Strike Of The Faults Apparently Had Little Or No Effect On Where Quartz Was Deposited, But The Veins Are Widest In The Steepest Parts Of Their Host Fissures. The Distribution Of Gold Within The Quartz Shows An Even Weaker Relationship To Structure.

Comments on the geologic information

  • THE MONTEVERDE FM. INCLUDES RHYODACITIC TUFF AND ANDESITE LAVA, TUFF, AND AGGLOMERATE IN THE AREA SURROUNDING LIBANO. THE VOLCANIC SECTION IN THE VICINITY OF THE MINE CONSISTS OF INTERFINGERING FLOWS, TUFFS, ASH, WATER-LAID TUFFS, AND AGGLOMERATES OF BASALTIC TO ANDESITIC COMPOSITION. DARK RED LATERITIC SOILS OBSCURE OUTCROPS.

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic
Significant No
Year of first production 1910

Mining district

District name Abangares District

Ownership information

  • Type Owner-Operator
    Owner W. C. Bennett (Cia. Minera Esperanza, S. A.)

Comments on the production information

  • ESTIMATED FROM THREE VEINS KNOWN TO HAVE BEEN STOPED.

Comments on the workings information

  • TEN LEVELS SPACED AT IRREGULAR INTERVALS BETWEEN 298 AND 190 M ELEVATION (LEVELS ARE DESIGNATED IN M ABOVE SEA LEVEL). TWO SHAFTS (LOCALLY CALLED WINZES), ONE INTERNAL AND ONE FROM THE SURFACE, CONNECT THE LEVELS. ACCESS TO THE MINE IS PROVIDED BY THE 298 LEVEL ADIT.

Comments on development

  • DEPENDING ON SOURCE, THE FIRST PRODUCTION WAS EITHER BETWEEN 1910 AND 1915 FROM THE N WORKINGS KNOWN AS LA POCHOTA OR IN 1921 BY THE GUANACASTE DEVELOPMENT CO. BOTH SITUATIONS ARE PLAUSIBLE. BY 1926, SEVERAL UNDERGROUND LEVELS HAD BEEN DUG AND CIA. MINERA SACRAFAMILIA WAS THE OPERATOR. LITTLE IS KNOWN FROM THE PERIOD 1926 TO 1972 BEFORE BULORA CORP., LTD., THROUGH ITS SUBSIDIARY ESPERANZA MINES CORP., CARRIED OUT UNDERGROUND MAPPING AND SURFACE DIAMOND DRILLING PROGRAMS. THE PROPERTY WAS SOLD TO W. C. BENNETT AND HIS ASSOCIATES (OPERATING AS CIA. MINERA ESPERANZA, S. A..), WHO HAVE OPERATED THE MINE NEARLY CONTINUOUSLY TO THE PRESENT, EXCEPT DURING MID-1982 THROUGH MAY 1984 WHEN IT WAS LEASED TO MALLON MINERALS CORP. OF DENVER, COLORADO.

Reference information

Bibliographic references

  • Deposit

    BENNETT, EVAN, 1939, GOLD MINING IN COSTA RICA: ENG. MIN. J., V. 140, NO. 1, P. 56-58.

  • Deposit

    WILLIAM BENNETT, OWNER, ORAL COMMUNICATION, 1986.

  • Deposit

    ORGANIZACION DE LOS ESTADOS AMERICANOS, 1978, DIAGNOSTICO DEL SECTOR MINERO: SAN JOSE, ORGANIZACION DE LOS ESTADOS AMERICANOS, 91 P.

  • Deposit

    U.S. GEOLOGICAL SURVEY, DIRECCION GENERAL DE GEOLOGIA, MINAS E HIDROCARBUROS, UNIVERSIDAD DE COSTA RICA, 1987, MINERAL RESOURCE ASSESSMENT OF THE REPUBLIC OF COSTA RICA: U.S. GEOLOGICAL SURVEY MISCELLANEOUS INVESTIGATION SERIES MAP I-1865, 75 P.

General comments

Subject category Comment text
Deposit THE AZUL AND BLANCA VEINS VARY FROM CONTINUOUS QUARTZ STRUCTURES OF NEARLY CONSTANT WIDTH TO TIGHT OR GOUGE-FILLED N- AND NE-TRENDING FAULTS CONTAINING QUARTZ PODS LOCALLY. THE QUARTZ IS IN COCKSCOMB BANDS AND VUGS. MOST ORE HAS BEEN MINED FROM THE AZUL VEIN ALONG A STRIKE LENGTH OF 600 M AND A DEPTH OF 130 M. THE VEINS FORTUNA, MARAVILLA, CHIRICUACO, 40, AND CIEBO ARE ALSO INCLUDED IN THIS DEPOSIT.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-MAR-1986 Howe, Stephen S. (Cox, Dennis P.) U.S. Geological Survey PARSED HOST ROCK AND ASSOCIATED ROCK INFORMATION FROM OLD SINGLE VALUED FIELD TO NEW MULTIVALUED FIELD
Editor 27-APR-1995 Mosier, Dan U.S. Geological Survey

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

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