Sentinel (U)

Project Summary

The Sentinel project is located approximately 50 km southwest of the city of Dickinson in southwest North Dakota and includes the Church uranium deposit.  The tenure consists of one mineral lease of approximately 2,107 hectares (5,203 acres) and two prospecting permits covering approximately 1,166 hectares (2,880 acres).  The Church deposit is situated on the mineral lease. Entrée obtained the project as part of the PacMag acquisition in June 2010.

The project is easily accessible via highway from Dickinson or from the capital city of Bismarck, 150 km east of Dickinson.  In the summer, most of the project area can be reached by a two wheel drive vehicle.  The Northern Pacific Railroad crosses the region and provides shipping facilities at the town of Belfield, 30 km to the north of the project.

Exploration work by PacMag in 2008 identified uranium, molybdenum and germanium mineralization associated with multiple shallow (< 20 m), stacked and sub-horizontal coal (lignite) seams.  The main uranium mineralized seam is widespread and consistent in thickness (0.6 to 1.2 m).  Resource estimate of the Church deposit was completed in 2009.  Current resources could be expanded by further drilling of the selected Church resource holes to test un-assayed lignite sections as well as drilling of other regional targets.

Mining in the late 1960's from a small open pit (now rehabilitated) that occurs within the Church lease is reported as producing approximately 40,000 tons of ore grading 0.175% U3O8 from near surface. This open pit and others within the district are all near surface, rarely exceeding a depth of 15 m.  Mining in the district ceased in the late 1960's when U3O8 was at $7 per pound. The recovery of molybdenum and germanium was not reported.

Exploration Activities 

• Metallurgical Testing (2009):  initial bench-scale column leach tests achieved recoveries above 90% uranium for Church deposit mineralization, without any need for pre-roasting.  The Church uranium mineralization may also be amenable to exploitation via low cost heap leaching of raw lignite ore.
• Inferred Resource for the Church deposit (JORC compliant, 2009)
• Drilling: 7,608 m in 410 drill holes completed (2008)

Links to Technical Reports 

July 2009 - Resource Estimation for the Church Deposit

Disclaimer: These resource calculations are not compliant with NI 43-101 standards and are presented for information only. The Company cautions that these historical resources can not necessarily be relied upon.

Geology

The Church deposit occurs within the sandstone, siltstone, claystone, lignite and limestone of the Sentinel Butte Member which is part of the Tertiary Fort Union group.  Uranium, molybdenum and germanium mineralization is hosted by several discrete lignite seams that range in thickness from 0.3 to 3 m and are separated by sedimentary interburden that range in thickness from 1 to 20 m.  The lignite horizons are flat lying to very gently dipping.

The main uranium mineralized unit (Lignite 21) is widespread and consistent in thickness (0.6 to 1.2 m).  Uranium and molybdenum mineralization occurs predominantly at the top of 'Lignite 21'.

3D View Looking Across Church Deposit (10x vertical exaggeration)
Drill Collars (red circles), Sand Channels (gold polygons), Main Uraniferous Lignite 21 (grey polygon)

Drilling at the Church deposit was completed, using clusters of drill holes with nominal 100m x100m spacing. Locally close spaced drilling has been completed with a nominal 30m x 10m pattern.  Early phase drill sampling focused on only the upper and lower portions of the lignite seams and did not adequately sample the core zones of the lignite seams, in a belief that the mineralization was concentrated at the lignite margins.  Drill holes on the final phase of the drilling program showed that the core of the lignite seams was just as likely to contain mineralization as the outer zones.

A block model was created using a nominal block size of 25m (east) by 25m (north) by 0.3m (Z) for all mineralised lignites (Figure below). Grade estimation of U3O8 was carried out using the geostatistical method of Ordinary Kriging (OK), with high-grade restraining of very high grades.

Block grades (U3O8 ppm) dark blue 0 - 50, light blue 50 - 100, green 100 -200, orange 200-300, red 300 - 500, purple >500

Drill Collar Plan and Cross Section Location

Metallurgical Testing

Initial bench-scale column tests on small samples of raw lignite suggest that high uranium recoveries may be achieved by standard leaching processes.  These results are indicative only and need to be confirmed by larger scale testwork.

Last Updated: April 19, 2011