La Quebrada

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La Quebrada Drill Map and Results | NI 43-101 Mineral Resource Estimate

The 100% owned La Quebrada project is located in Region IV of Chile, approximately 415 km north of Santiago and 40 km northeast of the coastal city of La Serena. The approximate centre of the property is located at UTM coordinates 303000 E / 6702500 N (Provisional South American Datum 1956, UTM Zone 19 South).

Mandalay has received SEA (Servicio de Evaluación Ambiental) approval for its third phase of core drilling and has an access agreement with the surface rights owner, the Comunidad Agricola Hoya de Caldera de Elqui.

Geology and Mineralization:
The principal host for copper-silver mantos at La Quebrada is arkosic limestone beds within the upper Cretaceous Arqueros Formation and the overlying basal Cretaceous Quebrada Marquesa Formation. These carbonate units, up to 50 metres thick, occur in restricted, sediment-starved sub-basins of which several have been identified to-date on the property. Most contain disseminated, stratiform bornite-chalcocite-chalcopyrite mineralization. Mantos also occur along permeable andesite flow tops in at least five horizons within the lower Arqueros Formation. Click on figure below to see the La Quebrada district geology map.

Historical drilling has demonstrated stratiform mineralization over an area of 1.5 by 1 km at the Casa de Piedra target and 1 by 2 km at the Dalmatas target. Mapping also revealed new manto targets at Leoncita. In addition, several other manto occurrences have been identified throughout the La Quebrada property (20,100 hectares) that have yet to be explored. Immediately adjacent to the Company’s Casa de Piedra target, Minera San Germino is currently extracting the same Cu-Ag manto (1.13% Cu, 11 g/t Ag) from the 540,000 t/a Tugal open pit mine and a few km away, in the Talcuna district, three companies are mining similar material underground from the Quebrada Marquesa Formation.


Exploration History:
Over the past 40 years, the property has been explored sporadically by various mining companies including the United Nations – ENAMI joint venture, Placer Dome, Noranda and Teck.

Mandalay Exploration at La Quebrada:
The Company completed a maiden NI 43-101 compliant mineral resource estimate for the Casa de Piedra deposit in July of 2012.  Geological mapping, trenching and drilling have defined three superposed, nearly horizontal, bedded copper-silver horizons (“mantos”) at the Casa de Piedra sector of the La Quebrada project.  These mantos each range in thickness from 1 to 12 m, with intervening intervals of thin, discontinuous mineralization. A total of 41 core holes for 7,430 m were drilled by Mandalay during 2011 (17 holes for 2,932 m) and 2012 (26 holes for 4,498 m) in the Casa de Piedra target; see Mandalay press releases dated August 9, 2011 and July 3, 2012). A continuous sample of HQTW-sized core was extracted from each hole.

Initial Resource Estimate; Casa de Piedra Section of the La Quebrada Project:

(Effective June 30, 2012)

Category Resource
Cu Grade
(cont. lbs)
Ag Grade
(cont. oz)
Indicated Resources 34.1 0.6 459 10 11.2
Inferred Resources 1.0 0.6 13 11 0.4


1. CIM definitions were followed for Mineral Resources.
2. The La Quebrada Mineral Resource estimate was prepared under the supervision of Ronald Luethe, an Idaho registered Professional Geologist, an American Institute of Professional Geologists (“AIPG”) Certified Professional Geologist and a Qualified Person under NI 43-101; it was reviewed and verified by Michael Easdon, an Oregon Registered Professional Geologist (No. 243), an AIPG Member (CPG-07646), and an Independent Qualified Person under NI 43-101.
3. Mineral Resources are estimated using Inverse Distance Cubed interpolation into 25m*25m*manto (as defined below) thickness blocks, with grade estimates for each manto based only on composites from the same manto.
4. Inferred resource is defined by a minimum of one drill hole within a search radius of 300 metres (“m”) in the same manto.
5. Indicated resource is defined by at least two drill holes within a search radius of 300 m in the same manto.
6. Mineral Resources are reported at a cut-off grade and thickness of 0.3% Cu over 3 m.
7. A bulk density of 2.71 t/m3 was used
8. Numbers may not add due to rounding.


The full technical report was filed and available on under the Company’s profile and is available here

Qualified Person:
Ronald Luethe, General Manager of Minera Mandalay Ltda., is an AIPG Certified Professional Geologist and a Qualified Person as defined by NI 43-101.  He has reviewed and approved the technical and scientific information on La Quebrada contained on this web page