New Mexico

Marquez-Juan Tafoya

Project Highlights

Project Details


The Marquez-Juan Tafoya Project includes the Marquez-Juan Tafoya Deposit, together with the Southeast Deposit located about 1 mile to the southeast. With enCore’s acquisition of the Juan Tafoya property through its purchase of Westwater’s assets, the Company has merged the property with its wholly owned Marquez property to consolidate the largest uranium deposit in the eastern Grants Uranium District.

The Marquez-Juan Tafoya property is located approximately 20 miles (32 km) north of the town of Laguna. enCore controls the mineral rights through private land leases totaling 18,596 acres (7,524 ha).

The property was extensively explored by Kerr McGee Corp. and Bokum Resources Corp. (Bokum) during the 1970-80s, with 926 holes, totaling about 1.9 million feet drilled. During development of the property for mining Bokum sunk a 14-foot diameter shaft to a depth of 1,842 feet near the center of the Marquez-Juan Tafoya Deposit. The historical Bokum shaft could potentially be used in future mine development, however it will need to be inspected and rehabilitated should enCore conduct a mine feasibility study.

Following completion of a Pre-Feasibility study and mine planning, in 1978 Kerr McGee sold 50% of the project to joint venture partner Tennessee Valley Authority. The joint venture elected to pursue underground mining operations by the mid-1980s. However, with falling uranium prices, the mine plan was shelved and the property was returned to the lease holders in the late 1980s. Subsequently both the Kerr McGee and Bokum properties were acquired by other owners which subsequently led to enCore’s current ownership.  

Geology and Mineralization

The Jurassic age Morrison Formation Member hosting most of the sandstone-type uranium deposits in the Grants Mineral Belt is the Westwater Canyon sandstone. The Marquez-Juan Tafoya (as well as the Southeast) deposits primarily occur within the lower C and D sand units of this member. 

The uranium mineralization of both the Marquez-Juan Tafoya and Southeast deposits primarily occurs as the tabular-type, however lesser amounts of redistributed or roll-type mineralization is also reported within the Marquez-Juan Tafoya deposit.

Mineral Resources

A current mineral resource estimate for the Marquez-Juan Tafoya Deposit  is included in the 2021 Beahm and McNulty Technical Report and Preliminary Economic Assessment (PEA).(1) In addition a historic mineral resource estimate is available for the Southeast Deposit in the Geoffrey Carter, 2014 Technical Report .(2) 

In preparing both the current mineral resource estimate and the historical resource estimate both Beahm and McNulty(1) and Carter (2), respectively,  found that the analyses of data suggest the chemical U3O8 encountered during core drilling is enriched relative to radiometric or eU3O8 content. However, both Beahm and Carter were conservative in prepared their respective mineral resource estimates and did not adjust their estimates for chemical disequilibrium  

Mineral Resource Estimates

Table 1 – Mineral Resource Estimate for the Marquez-Juan Tafoya Deposit, McKinley County(1), and the Sunshine Deposit, Sandoval County(2), New Mexico

Marquez-Juan Tafoya Deposit: Minimum 0.60 GxT (ft % eU3O8 )Classification: CURRENT INDICATED TONS% eU3O8 POUNDS
C SAND1,426,3550.1564,455,706
D SAND5,685,2440.12013,678,258



(1)On June 9, 2021, enCore Energy  Corp filed the “Marquez-Juan Tafoya Uranium Project 43-101 Technical Report Preliminary Economic Assessment”, authored by Douglas L. Beahm, P.E., P.G., BRS Inc., and Terence P. McNulty, PE, PHD, McNulty and Associates, on SEDAR. Records indicate 926 holes totaling 1,889,140 feet were drilled on the combined Marquez and Juan Tafoya property. From the 604 holes completed in the vicinity of the Marquez-Juan Tafoya deposit Beahm used elogs from 192 and 337 mineralized intercepts, respectively, in making the mineral resource estimates for the  “C” and “D” sands. Drill hole spacing is on approximate 100 foot centers with additional closer offset drilling. 

The GxT contour methodology with a minimum cutoff of 0.60 Ft %eU3O8 , and a minimum mining thickness of 6 feet was used in preparing the resource estimates for the two sand levels of the Marquez-Juan Tafoya deposit.  

(2)On May 15, 2014, Broad Oak Associates filed a report entitled “NI 43-101 Technical Report on Mineral Resources: Juan Tafoya Uranium Project, Cibola, McKinley and Sandoval Counties, New Mexico USA”, Prepared by Geoffrey S. Carter, P.Eng. The historic mineral resource estimate for the property included an estimate for the Southeast Deposit. The resource estimate was made using the Inverse Distance Squared Method with a minimum cut-off grade of 0.05% eU3O8 .  The Southeast Deposit was estimated to host an Inferred Resource of 5,383,400 tons containing 12,292,600 pounds of eU3O8 with an average grade of 0.117%.

The mineral resources estimated for the Southeast deposits is classed in the “Inferred” category by Carter, (2), and are considered to be compliant with the CIM Code, as outlined by the Canadian Institute of Mining, Metallurgy and Petroleum “CIM Standards on Mineral Resources and Reserves, Definitions and Guidelines” (CIM, 2010).

Under “Rules and Policies” of NI 43-101 Standards of Disclosure the mineral resource estimate for the Southeast Deposit must be reported as a Historical Resource Estimate. A qualified person has not done sufficient work for enCore to classify the historical estimate as a current mineral resource estimate. The Company does not treat this historical estimate as a current mineral resource estimate, and the estimate should not be relied upon.

Figure 1. Map of the Marquez-Juan Tafoya Deposit showing GxT contour outlines of C and D Sands mineralization at a 0.60 GxT minimum cutoff, together with the Southeast Deposit.


The PEA for the Marquez – Juan Tafoya project includes an underground conventional mine operation with on-site mineral processing. For details of the mining and processing plan see Sections 16-18 of Beahm and McNulty 2021 PEA(1). The mine operations would be concurrent with a mine life of approximately 15 years. This is the first time since the initial discoveries that the two adjacent areas of deposit (Marquez and Juan Tafoya) have been consolidated and addressable by a single unified mine plan. 

The project, given the assumptions stated herein, would be profitable with a US$60 per pound selling price. In constant dollars the project is estimated to generate an IRR of 17% before taxes and has an NPV of approximately US$20.5 million at a 7% discount rate.

View Marquez-Juan Tafoya Technical Report


Project economic sensitivities were evaluated with respect to commodity price, resource recovery, mined grade, CAPEX, and OPEX.

The following table indicates the projects sensitivity to commodity price for IRR and NPV @ 7% discount rate. The breakeven commodity price is approximately US$56 per pound U3O8.

Table 2. Variation of the Internal Rate of Return (IRR) and Net Present Value (NPV) @ a 7% Discount Rate at uranium market prices over the range of US$56 to US$70/pound U3O8 .

Market Price per Pound U3O8IRR (%)NPV @ 7% Discount Rate US$ x 1,000
$                                56 5nil
$                                60 17$                         20,914 
$                                65 30$                         50,970 
$                                70 39$                         71,199 

Caution regarding Forward-looking statements

The reader should be aware the PEA is preliminary in nature and there is no certainty that the preliminary economic assessment will be realized. The PEA involves forward looking statements and Forward-looking statements are subject to a variety of known and unknown risks, uncertainties and other factors which could cause actual events or results to differ from those expressed or implied by the forward-looking statements, including, without limitation: The reader should refer to Beahm and McNulty’s PEA (2021) for more details on the associated risks. 

Douglas H. Underhill, PhD, CPG, enCore’s Chief Geologist, is the Qualified Person as defined under National Instrument 43-101 and has reviewed and verified the information presented throughout this enCore Energy website.