Montero Mining and Exploration Ltd

Montero Mining and Exploration Ltd

June 22, 2011 09:09 ET

High Grade Trenching and Drill Results Returns 9.27% TREO Over 6.45m Including 15.48% TREO Over 2.0m and 5.66% TREO Over 2.84m, Respectively, at Wigu Hill Rare Earth Project, Tanzania

TORONTO, ONTARIO--(Marketwire - June 22, 2011) -


Montero Mining and Exploration Ltd. (TSX VENTURE:MON) ("Montero") is pleased to announce additional trench and drill results from its Wigu Hill Rare Earth Element (REE) project in Tanzania. Wigu Hill is a Light Rare Earth Element (LREE) project with the mineral bastnaesite being the dominant rare earth mineral. Trenching and drilling to date at the Twiga and Tembo targets confirms the significant mineralization of the bastnaesite bearing carbonatite dikes across the Wigu Hill REE project. Exploration on these targets as well as the defined Tumbili Target will be included in Montero's upcoming NI 43-101 resource estimate and indicate the potential for a sizeable REE deposit.

Prior reconnaissance mapping and sampling results of a total of 209 grab samples from Wigu Hill averaged 7.4% Total Rare Earth Oxides (TREO). High grade values were traced across the entire 6.2km west-east strike of the carbonatite complex, including 11 values ranging from 7.9% TREO to a high grade value of 26.2% TREO which occurred on the eastern portion of Wigu Hill on what has been designated the Tembo Target.

To view the defined targets at Wigu Hill, please click to view:

The carbonatite dikes evaluated at the Tembo target are 950m north-west of the Twiga target where high grade TREO results have been obtained (see news releases dated 11/04/2011 ( and 16/05/2011 ( The results returned from the trenching and drilling at Tembo reflect a more dolomitic carbonatite composition but with evenly disseminated bastnaesite mineralization which confirms the continuity of the dikes. The highest values of up to 15.48% TREO were returned from trenches and up to 5.66% TREO from the drill holes.

Dr. Tony Harwood, President and Chief Executive Officer of Montero, commented "We are very encouraged by the continued high grade trench and drill results obtained from the Tembo target that, combined with the excellent results obtained last month from the Twiga target, will be included in the Montero's first NI 43-101 REE resource estimate for Wigu Hill. Mapping and further sampling on other targets at Wigu Hill, notably from the Tumbili target, indicates the potential for a sizeable high tonnage and high grade bastnaesite bearing mineralized system which, with further exploration and drilling, we will bring to account."

Tembo Target: Trenching and Mapping

Trenching and mapping at the Tembo target were focused in the area where the regional grab sampling returned high grade TREO results. A set of anastomosing, sub-parallel dolomitic, bastnaesite-rich carbonatite dikes were mapped over a strike distance of over 300m up the eastern slopes of Wigu Hill. The dikes vary in thickness from 0.5m to 4.00m, but in areas where they coalesce, their combined thickness reaches 7.15m grading at 6.28% TREO. Carbonatite breccia material occurs as selvage in some dikes and in places occupies the entire zone between adjacent dikes. The north-westerly trending dikes are near vertical with dip measurements showing some steep dips to the NE and some to the SW with %TREO values shown in Table 1.

Further up the hill the strike of the dikes swings easterly on a bearing of 070° north and here the dips are consistently steep to the north. Three sets of dikes are exposed, one a composite set of up to 4 dikes, and then one each to the north and south. These three dike sets are separated by between 25m to 50m. Crystalline, bastnaesite-rich material can be observed as resistant relicts on the surface of the carbonatite outcrops.

Trench assays demonstrate that the rare earth mineralisation is mainly concentrated within the fresh, crystalline and compact carbonatites (Table 2), while locally lower grade concentrations of mineralisation (<2% TREO) are to be found in the associated breccia zones and zones of intense to weak carbonate alteration of the gneisses.

Trench NoFromToWidthTREO %
Trench 416.0021.005.007.98
Trench 924.5031.006.504.50
Trench 1125.0028.003.005.20
Trench 120.705.004.305.59
Trench 1325.5030.004.503.25
Trench 147.7010.002.304.97
Trench 155.5010.204.705.42
Table 1. Total Rare Earth Oxide values from the north-westerly trending Tembo Target bastnaesite-rich carbonatite dikes. Apparent widths are very close to true widths.
Trench NoFromToWidthTREO %
Trench 1911.0014.003.007.03
Trench 2019.5022.002.506.53
Trench 228.5012.504.008.59
Trench 240.404.504.1010.69
Trench 2613.9016.702.809.26
Trench 272.505.703.205.70
Trench 303.006.503.505.84
Trench 30B0.
Trench 345.
Trench 353.006.503.506.00
Trench 360.805.805.0010.64
Table 2. Total Rare Earth Oxide values from the easterly trending Tembo Target bastnaesite-rich carbonatite dikes. The apparent widths are very close to true widths.

Discussion of individual trench results

The trench assay results from the Tembo target were received and assessed and evaluated for quality control. On review the assays from Genalysis conformed well to quality control evaluation.

To view a map of Tembo trench, click here:

To view a map of the Tembo target geology, click here:

Some good continuity of individual dikes can be traced along the strike, but often numerous narrow dikes form an anastomosing network in between the trenched sections and it is here that samples returned anomalous TREO values.

Tembo Target: Drilling

Road access and pad construction was undertaken only on the upper reaches of the Tembo target and as a consequence of this, it was only possible to drill the uppermost easterly trending dikes before the onset of the rainy season, when drilling activities were suspended. Five boreholes (totalling 540m) were drilled on the East-West trending dikes and intersected three sets of carbonatite dikes at depths ranging from 73m to 134m below drill collar. The best zone of mineralisation is from a set of 4 dikes at 3.33% TREO over 7.65m true width in BH TE002 and 3.15% TREO over 7.68m in BH TE003 (Table 3).

The occurrence of carbonatite breccia is more extensive on drill sections 7 and 6 moving westward towards BH TE001 which is weakly mineralised and grades at 0.80% TREO over a true width of 17.80m. The continuity of the carbonatite dikes is consistent and could be traced from surface down to a depth of over 60m. The main dike set, which can be traced along strike on surface for greater than 150m, has good continuity along strike and down dip and grades 2.39% TREO over a maximum true thickness of 18.40min BH TE005R. The dip of the dikes and breccia zones is consistent to the north at between 85° to 70°.

True Thickness
Table 3. Total Rare Earth O­xide values from core boreholes drilled on the south-easterly trending carbonatite dikes at Tembo.

Significant widths of continuous mineralisation have been encountered, namely 3.15% TREO over 7.68m, and in BH TE001, a broader zone grades at 2.39% TREO over a true thickness of 18.40m.

Discussion on the analytical procedures:

Certified Standard: A certified standard was prepared by AMIS (African Mineral Standards) in Johannesburg, South Africa. This standard was used as reference material in the analysis of the samples reported here.

Analytical Laboratory: The first batch of trench samples was analysed by Genalysis in Perth. Samples were sent to Johannesburg where sample preparation was undertaken and a 300-500gm pulp sent to Perth for analysis of the rare earth elements sodium peroxide fusion in nickel crucibles and ICP-MS, an analytical package to 22 elements. The balance of the trench samples and the entire borehole core samples presented here were analysed by ALS Chemex in Vancouver after sample preparation was undertaken at their facility in Mwanza, Tanzania. The AMIS certified standard was inserted as sealed packets at intervals of 20 samples at both laboratories. Analyses for high-grade REE elements are performed by lithium meta-borate fusion and ICP-MS, an analytical package of 38 elements. Rock forming elements are analysed by lithium meta-borate fusion followed by dissolution of the melt and ICP-AES analysis. An option is available to analyse over limit REE's by ME-OGREE. For this batch of assays numerous samples were analysed for Ce, La and Pr to quantify the higher values of these elements.

Definition of TREO: The use of the term TREO (Total Rare Earth Oxides) in this release includes only the 15 defined rare earth oxides, namely:- Most abundant – CeΓééOΓéâ, LaΓééOΓéâ, NdΓééOΓéâ, PrΓééOΓéâ and SmΓééOΓéâ (referred to as light rare earth oxides). These 5 Light Rare Earth Oxides make up over 99% of the rare earth element content, particularly for values >1% TREO. Others:-EuΓééOΓéâ, ErOΓéâ, DyΓééOΓéâ, GdΓééOΓéâ, HoΓééOΓéâ, HfOΓéé, TbΓééOΓéâ, TmΓééOΓéâ, LuΓééOΓéâ and YbΓééOΓéâ (Pm was not assayed) are present in minor to trace amounts only. Values for elements such as Y or Nb, are not included and have not been reported here.

QA/QC: Montero has used blanks, field duplicates and one analytical standard to monitor the sampling and analytical quality. Results to date for the blank and field duplicates show acceptable quality for the main REEs of interest. The standard used was prepared on behalf of Montero using material from Wigu Hill and has certified analytical values for Ce, La, Pr and Sm based on analyses from 16 different laboratories. A review of the results reported by ALS Chemex and performed by AMEC indicates that these meet the required level of analytical quality. Chain of custody protocols require the signing and maintenance of logs and receipts each time the samples are picked up from or delivered to a new location. All shipping sacks are sealed with a numbered tag, the removal of which is recorded upon receipt by the laboratory.

Qualified Person's Statement

The technical information contained in this press release has been reviewed by Mr. Mike Evans, M.Sc. Pr.Sci.Nat., who is a qualified person for the purpose of National Instrument 43-101 and a consulting geologist to Montero.

About Montero Mining & Exploration

Montero Mining and Exploration Limited is a mineral exploration and development company focused on the development of our flagship Wigu Hill Rare Earth Element Project in Tanzania. The Wigu Hill project is a high grade undeveloped Light Rare Earth Element deposit that the company is currently drilling to produce a NI 43-101 compliant resource estimate.

Rare Earth Elements (a group of 15 metals) are critical in the advancement and development of emerging "green" technologies and high-tech applications such as electric and hybrid vehicles, wind and hydro power turbines, energy efficient lighting, LCD screens, MRI, x-ray machines and neodymium-based magnets crucial to ear-buds, MP3 Players, microphones, mobile devices and other computing equipment. Currently China produces 97% of world supply of REE's and these are becoming increasingly critical to both 21st century technological progress and environmentally sustainable development. With the rising prices of REE's and China's control over export quotas, it is becoming imperative that the rest of the world develops new rare earth resources to meet the increasing demand from "green" technology.

Montero's growth strategy is to develop the Wigu Hill REE project and to bring this to account by eventual production and cash flow. Montero plans to operate in an environmentally and socially responsible manner, adding value to all stakeholders.

Signed. Dr. Tony Harwood - President and CEO

CAUTIONARY STATEMENT: This news release contains forward-looking information which is not comprised of historical facts. Forward-looking information involves risks, uncertainties and other factors that could cause actual events, results, performance, prospects and opportunities to differ materially from those expressed or implied by such forward-looking information. Forward looking information in this news release includes, but is not limited to, Montero's objectives, goals or future plans, and the estimated timing and cost of the exploration of the Wigu Hill Project. Factors that could cause actual results to differ materially from such forward-looking information include, but are not limited to, those risks set out in Montero's public documents filed on SEDAR. Although Montero believes that the assumptions and factors used in preparing the forward-looking information in this news release are reasonable, undue reliance should not be placed on such information, which only applies as of the date of this news release, and no assurance can be given that such events will occur in the disclosed time frames or at all. Montero disclaims any intention or obligation to update or revise any forward-looking information, whether as a result of new information, future events or otherwise, other than as required by law.

Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

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