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Spain - Tungsten/Gold

Logrosan Minerals Limited Exploration Status Summary

Logrosan Minerals Limited is a special purpose joint venture vehicle held by Metal Tiger PLC (MTR) and Mineral Exploration Network (Finland) Ltd (MEN). Logrosan Minerals Limited is the operating company for the Logrosán Exploration Project (‘the Project’). The Minerals Exploration Network group is a fast moving low-cost exploration project developer and incubator with a portfolio of exploration holdings in Spain and Finland. At the joint venture onset, the Project consisted the most advanced of the MEN Spanish holdings, with detailed soil geochemistry, stream sediment and ground geophysics coverage defining significant tungsten and gold exploration targets.

Location, Mineral Tenement and Land Tenure Status

The Logrosán Project, is located in a geologically prospective, under-explored and mining friendly jurisdiction in west-central Spain. Within the province of Cáceres in the Extremadura autonomous region, it is served by a well-developed and maintained road network, with good power, water and telecommunications infrastructure. The Project enjoys the full support of the regional and local government and administration.

The Project covers an area of 310.21 km2 consisting of the Antonio Caño, Zorita, San Cristóbal and Mari Hernandez Exploration Licences and the San Cristóbal Sur Exploration Licence Application.  Four of the five concessions are adjacent and contiguous, whilst the Mari Hernandez is located 13.5km to the north of the main group. See Table 1 for licence details.

The Zorita and Antonio Caño licences are host to the main known tungsten occurrences constituting Target 1 and Target 2 respectively. The Zorita licence application was lodged on 1 September 2014 and awarded on 18 June 2015.

Table 1: Spanish Concessions held by JV local subsidiary Logrosán Minera SL
Asset Status License Expiry Date License Area (km2) Comments
Antonio Caño Exploration Licence (#10314-00) Exploration 1 December 2016 37.22  Renewal application lodged, fees paid. Renewable three times to a maximum of 9 years
Zorita Exploration Licence (# 10C10332-00) Exploration 18 June 2018 85.08 Renewable to max. 9 years
San Cristóbal (#10C10321-00) Exploration 16 June 2019 43.81 Renewable to max. 9 years
"Maria Project" Mari Hernandez Permit (#10313-00) Exploration 30 October 2016 40.09 Renewal application lodged, fees paid. Renewable to max. 9 years
San Cristóbal Sur (Application #10358-00) Exploration License Application N/A 31.74 Exploration License Application

Total area excluding Logrosán town: 238 km2

Figure 1: Location of Logrosán Exploration Project in Spain
Figure 2: Map Showing the Logrosán Exploration Project Concessions
Figure 3: Locations of Current Logrosan Tungsten and Gold Exploration Targets and Anomalies

Exploration Undertaken by Previous Parties

MEN commenced work on the Logrosán Project in October 2013 following a detailed target area assessment. Key factors which contributed to the selection of the area were; the availability of high quality regional geological survey data showing prospective geology and structure; known gold occurrences within the area; a long history of mining activity in vicinity and surrounds; and a pro-mining regional administration, with a fast and transparent licence application and approval process.

There had been little systematic exploration in the area since the early 1980s gold price peak.

Exploration work undertaken to date includes collection and analysis of 41,784 soil samples, 2,147 line kilometres of ground magnetics geophysics, 16 line km of induced polarisation (IP)/resistivity electromagnetic tomography and 327 stream pan concentrate samples. These samples evidence the presence of tungsten and gold.

The results of the initial exploration works were catalogued for interpretation in a GIS. Plots of the geochemical results and geophysics show areas of elevated, lead, zinc, tin, arsenic and tungsten in soil; these have good correlation with each other and with perceived structures interpreted from the geophysics. Gold in pan concentrate also correlates well with the base metal and arsenic anomalies. Interpretation has delineated six target areas for detailed investigation, with four targets prioritised for the 2015 JV exploration programme, two to focus on tungsten and two targeting gold.

Neighbouring Properties

There are three public listed exploration and pre-production development companies located within the surrounding region. The W Resources Plc La Parrilla tungsten mine is 43km south-west of the Project area; the Emerita Resources Corporation Las Morras Gold Project is 6km to the south; and the Berkley Resources PLC Gambuta uranium deposit is 40km north.

Historical Mining

There is long history of mining in the Logrosán area, with known workings for tin, tungsten, copper, iron and phosphate. In the centre of the Project area, associated with a prominent intrusion, are surface tin workings which have been dated as being active from the Bronze Age through to Romano-Celtic times. The Romans also mined gold and silver in the wider region. There are six historical mines located within or close to the Project concessions, the last of which mined Phosphate and was closed in the 1940s. A number of small scale mine workings and mineral trials have also come to light during the MEN exploration work.


The Project area is located within the inner zone of a complex Precambrian to Tertiary age multi-stage volcanogenic ring complex. This complex is associated with a north-west striking regional thrust belt and a corridor of intersecting south-west orientated faults. The exploration model is for intrusion related veins, sheeted veins, dikes, skarn and replacements with gold, tungsten and base metal mineralisation. The centre of the Project area is dominated by a mica-granite intrusion which forms the San Cristóbal mount, this is surrounded by undifferentiated shale and greywacke. Large structures can be seen to cross the region as evidenced by the topography and, within the Project, by the companies’ geophysics.

Figure 3: Photograph taken from the Summit of San Cristóbal Mount in the Centre of the Project Area

Exploration Work Methodology

The exploration work is undertaken by a core crew of four geology graduates who work under the direction of the Chief Geologist who has over 33 years’ experience in mineral exploration. The exploration work is carried out in line with standard best practices, with an emphasis on covering ground quickly and cost efficiently.

Soils sampling is undertaken on a 200m or 100m grid with 20m sample spacing. All soil samples are analysed in the field by using an InoveX Alfa XRF; once an area is completed a decision is made whether to further analyse samples with a laser ablation ICP-MS in the MEN laboratory in Finland. A selection of soil samples are externally analysed by ALS Laboratories in Seville. The work is undertaken to defined QA/QC procedures.

Panned concentrate sampling is employed to determine the presence and distribution of gold. Stream sediment samples were systematically collected from streams and drainage channels across the Project area, these consisted 20 l of collected material panned down to a concentrate. The concentrate is visually inspected and the number of gold flakes counted. A selection of gold flakes are photographed using a microscope to determine their size and morphology, with a sub-set of flakes subject to micro-probe analysis.

Ground magnetic geophysics is undertaken on a 100m grid with 2m survey points, using Geometrics (G-859 & G-856) magnetometers, and the IP/Resistivity geophysics is undertaken using a 4 electrode (ALFA-12) system.

Trench and channel sampling, with ALS analysis, was also utilised to confirm tungsten mineralisation on Target 2 prior to the commencement of drilling.

Drilling targets were based on interpretation of the sampling, geophysics and geology with the aid of a comprehensive geographical information system (GIS) for the Project.


Under the terms of the MTR joint venture, there is a provision for up to 5,000m of shallow rotary air blast (RAB) drilling. The RAB drilling is undertaken by a Dando Terrier track mounted drill rig fitted with a mast dump for inclined drilling up to 45 degrees from vertical. The holes are shallow, with the purpose of confirming the presence and indicative scale of sub-surface mineralisation intersections only. The drilling is not for the purposes of Resource definition, but as a minimal environmental impact alternative to trenching. The drill holes are arranged on profiles set across the soil geochemistry and ground magnetic anomalies with the azimuth of each drill hole perpendicular to the perceived mineralised trend.

All tungsten drilling samples are analysed, quantitivly, in-house by XRF and qualitivly for wolframite fluorescence by ultraviolet lamp inspection. Based on these findings drilled intervals with identified tungsten mineralisation (plus the corresponding footwall and hanging wall samples) are submitted to ALS for external analysis.

ALS analysis consists sample preparation (code CRU-31, SPL-22Y, PUL-32 and DRY-21 and quality control CRU-QC and PUL-QC) followed by Trace Level XRF Analysis (package ME-XRF-05) for tin (Sn) and tungsten (W). The lower resolution of the testing is Sn: 5 parts per million (ppm) and W: 10ppm. ALS results are issued with the appropriate QC certificates for in-laboratory QA/QC. Duplicates and pulps are retained. ALS conduct their sample preparation in their Seville (Spain) facility and undertake the XRF analysis in their Vancouver (Canada) laboratory.

Initial Exploration Results

Tungsten Review

The exploration for tungsten (W) in the Logrosan Project has centred on two distinct target areas which were identified on the basis of previous soil geochemistry and ground magnetic surveys. These targets are separated by a distance of 12km; Target 1 is near the centre of the Zorita Licence and Target 2 is located in the south-west of the Antonio Licence (see Figure 2).

Between April – June 2015, as part of the Metal Tiger JV work programme, both targets were subject to first-pass RAB drilling to confirm the near surface tungsten mineralisation and grade.

The results of this preliminary drilling have been very encouraging, with significant strike length tungsten mineralisation and high grade tungsten intersections outlined.

Review - Tungsten Target 1

Tungsten Target 1 contains the larger of the two tungsten-in-soil anomalies (up to 636ppm W), measuring 1.2km long by 200m wide and trending NNE-SSW. Drilling, consisting a total of 17 holes (268m) drilled, to an average depth of 16m, on two profiles drilled perpendicular to the anomaly strike at a 380m separation. Drill sample assays have confirmed high-grade tungsten mineralisation in the north and the centre of the target soil anomaly and the soil anomaly remains open (untested by drilling) for a distance of 700m to the south and for 120m to the north.

Drill assay results, conducted by ALS Laboratories, returned a maximum WO3 grade above the analytical detection limit of 0.63% (5000ppm) and an average grade across all Target 1, drill samples submitted, of WO3 0.09%. The highest intersections in holes MW003 (10m WO3 >0.24%, including 2m >0.63%) on profile 2 and MW010 (with total intersections of 10m >0.2% and 2m WO3 0.37%) on profile1, are separated by up to 400m of potentially continuous mineralisation. It should be noted that the tungsten concentration of workable ores typically starts from 0.10% WO3.

Target 1 requires further shallow drilling profiles to delimit the full extent of the tungsten mineralisation width and strike to the north and south, and deeper drilling to delineate mineralisation vertical depth extension, grade and thicknesses.

Table 2: Significant Tungsten Drill Hole Intersections, Logrosán Target 1
Hole ID From (m) To  (m) Intersection Width * (m) WO3 (%) Notes
MW003#2 3.60 13.60 10.00 0.24 including 2m @ > 0.63% WO3 (above detection limit)
MW004#2 1.63 9.63 8.00 0.19 including 2m @ 0.34% WO3
MW005 1.63 3.63 2.00 0.10  
MW009 7.63 9.63 2.00 0.20  
MW010#1 1.54 3.54 2.00 0.31 Holes MW010 and MW011 were drilled to target the same structure from opposing directions.
5.54 9.54 4.00 0.20
11.54 13.54 2.00 0.37
15.54 17.54 2.00 0.23
MW011#1 5.68 7.68 2.00 0.10  
11.68 13.68 2.00 0.25

* Note that drill intersection widths do not necessarily represent the true thickness of the mineralisation as insufficient drilling has been completed to calculate the actual dips of the veins/structures.
#2 adjacent holes on profile 2.
#1 adjacent holes on profile 1.

Review - Tungsten Target 2

Tungsten Target 2 is located over a central, distinct, tungsten-in-soil anomaly ranging up to 565ppm W and measuring 700m long by up to 150m wide (Figure 2). This central soil anomaly is orientated in a NE-SW direction, and coincides with a 1.6km long geophysical structure. There are three further weaker anomalies associated with structures running parallel to it, one 250m to the north-west and two to the south-east, at 325m and 700m separation to the central anomaly.

Target 2 has been investigated with a total of 65 holes to an average of 20m depth, 1,300m in total. The central W anomaly has good drill coverage with a total of 26 holes on 8 profiles over a total strike length of 570m. Two further profiles have been drilled along strike at 560m NE and 500m SW of the outlying profiles (on the central zone drilling). Both these profiles are located on the same 1.6km geophysical structure, but coincide with continuous strong Cr, Cu, Sn, As and weak W anomalies.

Assays from all analysed drill samples on Target 2 average WO3 0.04% and a maximum of WO3 >0.63% (above upper detection limit) located in the central anomaly. Significant tungsten intersections are outlined in Table 2.

There is a 400m on-structure strike distance between hole LM014 (on profile 3) with 2.70m WO3 >0.32% (including 2m @ > 0.63%) and hole LM08 (on profile 7) with 8m at WO3 0.32% (including 2m @ 0.49%WO3 & 0.1% SnO2).

Target 2 requires deep drilling to delineate tungsten mineralisation vertical depth extension, grade and thicknesses, and to establish the Resource potential of the area.

Table 3: Significant Tungsten Drill Hole Intersections, Logrosán Target 2
Hole ID From (m) To  (m) Intersection Width * (m) WO3 (%) Notes
LM001#4 19.57 21.57 2.00 0.15  
LM002#4 3.15 7.15 4.00 0.18  
LM003 13.60 17.60 4.00 0.08  
LM008 5.52 13.52 8.00 0.32 including 2m @ 0.49%WO3 & 0.1% SnO2
15.52 17.52 2.00 0.32  
LM012#3 7.48 13.48 6.00 0.08 including 2m @ 0.11%WO3
LM014#3 11.30 14.00 2.70 >0.32 including 2m @ > 0.63% WO3  (above tungsten detection limit of 5000ppm)

* Note that drill intersection widths do not necessarily represent the true thickness of the mineralisation as insufficient drilling has been completed to calculate the actual dips of the veins/structures.
#4 adjacent holes on profile 4.
#3 adjacent holes on profile 3.


Mr Nick O'Reilly (MSc, DIC, MAusIMM, FGS), is a qualified geologist who meets the criteria of a qualified person under the AIM Rules - Note for Mining and Oil & Gas Companies, has visited the Project Area, and reviewed the technical information contained herein. Mr O’Reilly is a consultant working for Mining Analyst Consulting Ltd which has been retained by Metal Tiger PLC to review the work undertaken on the Logrosán Exploration Project.