Published on Wednesday September 07 2011
Northern Minerals (ASX: NTU) has received further exciting Heavy Rare Earth Element (HREE) results from drilling at its Browns Range project in northern WA (see Figure 1 below), which have confirmed and extended the high value HREE mineralisation.
The results feature several significant intersections with Total Rare Earth Oxide (TREO) in excess of 1%. The assays are from the first half of an 11,000m RC drilling program at Browns Range, and follow the previous results announced in July 2011.
The Company now has assays from the first 72 holes from the 134 holes drilled to date, covering four highly prospective areas of mineralisation (Area 5, Area 5 North, Gambit and Wolverine - see Figure 2 below). Best results from the 61 holes assayed in this recent batch include (all from Gambit prospect):
· NMBRRC055 - 11m @ 2.07% TREO (0.19% Dy2O3) from 35m
· NMBRRC057 - 18m @ 1.19% TREO (0.11% Dy2O3) from 51m
· NMBRRC045 - 9m @ 1.68% TREO (0.15% Dy2O3) from 86m
· NMBRRC046 -11m @ 1.07% TREO (0.10% Dy2O3) from 48m
· NMBRRC051 - 7m @ 1.61% TREO (0.15% Dy2O3) from 66m
· NMBRRC059 - 3m @ 2.31% TREO (0.21% Dy2O3) from 42m
· NMBRRC056 - 3m @ 1.48% TREO (0.13% Dy2O3) from 45m
· NMBRRC048 - 3m @ 1.54% TREO (0.14% Dy2O3) from 30m
NB - TREO: Total Rare Earth Oxides - Total of La2O3, CeO2, Pr6O11, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb4O7, Dy2O3, Ho2O3, Er2O3, Tm2O3, Yb2O3, Lu2O3, Y2O3
A key feature of the results is the xenotime hosted REE mineralisation, and the dominance of high value heavy REE. HREO accounts for an average 83% of the TREO from Gambit, with high levels of dysprosium a key feature. With limited sources of new and available global supplies, dysprosium has become of critical economic importance in the development and implementation of clean energy technology.
Managing Director George Bauk said the high levels of HREE, and the fact that the majority of other new and developing REE projects were dominated by light REE, made the Browns Range project unique.
"The high grades and the widths of these intersections at Gambit are giving us considerable confidence in the project, particularly with the exciting early indications from the completed drilling at the adjacent Wolverine which look even better," he said.
"It means Browns Range is really shaping up as a significant new discovery, and a potential HREE project of global significance," Mr Bauk said.
Another key advantage of the Gambit mineralisation is the relatively low levels of uranium and thorium with an average of only 37ppm uranium per 1% TREO (cut-off of 0.2% TREO). Metallurgical test work indicates that thorium is not directly associated with the xenotime mineralisation, and therefore can be readily removed.
The Company has also completed a number of holes at the nearby Wolverine prospect, with early analysis using a portable XRF unit returning outstanding HREE intersections over significant widths up to 40m. Laboratory assay results from several of these holes are pending, and the first are expected to be available within two weeks, with the remainder expected during October.
Northern Minerals has also received additional results from Area 5 North, which have revealed numerous low-grade REE (0.2% - 0.5%) intersections.
Mr Bauk said "At current REO prices the mix of high value HREE at Browns Range has an estimated in ground value of US$4,000/t for every 1% TREO".
"Our relatively simple processing route and high value HREE mix compared to other light REE projects gives us the confidence to develop a business model based on moving this project into concentrate production in less than five years. The ability to produce a high grade concentrate from a relatively simple flow sheet means significantly less time and capital costs than are typically associated with other light REE projects which can take 10 - 15 years to get into production and cashflow," he said.
At the Gambit Prospect, a total of 57 holes (NMBRRC034 - 072 & NMBRRC093 - 110) have been completed to date, with assays now received up to hole NMBRRC072. Holes were drilled 20-25m apart on north-south trending sections every 50 metres. Drill hole fences were directed alternately north and south to intersect an interpreted dominant east-west trending sub-vertical fault structure. The program was targeted at the peak of an east-west trending soil geochemical anomaly which extends over 2km (see Figure 3 below). The drilling completed to date has partly tested an area approximately 600m by 200m in extent (see Figure 4 and 5 below), with most of the drilling focused on an area 300m long.
Significant REE mineralisation (>0.2% TREO) has been intersected on all drill traverses across the 600m wide zone. Mineralisation is hosted by quartz-veined, silicified and/or hematitic arkosic sandstone, and appears to be controlled by an east-west trending fault structure(s), and northwest trending cross-cutting structures. The geometries of the mineralised zones are currently being assessed, with several possible interpretations for the orientations. One interpretation is that mineralisation is broadly sub-vertical, with higher-grade zones at fault intersections which create pipe-like plunging shoots.
Closer-spaced drilling (25m spaced sections) and core drilling is required in order to gain a better understanding of the structural controls on mineralisation. Further assay results from the remainder of the holes at Gambit (NMBRRC093 - 110) are expected next month.
Analysis of the assay results has shown the REE mineralization to be dominated by heavy rare earths with an average of 83% of TREO being heavy rare earths (above a cut-off of 0.2% TREO).
A total of 33 holes (NMBRRC073 - 092 & NMBRRC111 - 123) have been drilled at the Wolverine prospect. Holes have targeted a soil geochemical anomaly which extends for approximately 500m and is spatially coincident with a west northwest trending fault breccia structure. Drilling has been completed on north-south traverses approximately 25m apart over an area approximately 400m in strike length. Portable XRF measurements of samples from drill holes at the western end of the geochemical anomaly have indicated significant widths of REE mineralisation over a strike length of approximately 180m. Assay results are currently pending with results from holes NMBRRC073 - 092 expected within two weeks.