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Borralha Project

About Borralha Project

Borralha is a past producer of tungsten and was the second largest tungsten mine in Portugal after the Panasqueira Tungsten mine until its closure in 1985 as a result of a decline in tungsten price. The Borralha concession is located 60 km northeast of the major northern city of Porto and covers 127.5 km2 over several past producing zones. Tungsten occurred in numerous vertical and sub-horizontal veins as well as two breccia bodies, of which the Santa Helena breccia is the larger. Mining continued almost uninterrupted from 1903 to 1985, by French, British and German companies with two standstill periods from mid 1944 to late 1946, imposed by law, and from 1958 to late 1962. Production ceased in 1985 when tungsten prices dropped to sub-economic levels. The total production of wolframite and scheelite (tungsten minerals) concentrates from 1904 until the closing of Borralha, from underground and open pit sources, has been estimated at about 18,500 tonnes, although this number is approximate and may be substantially less than the true value.


Drilling

To date, Blackheath Resources has completed 6 diamond drill holes in the Santa Helena Breccia Zone, which is exposed at surface; and 2 drill holes drilled outside the breccia.

The Santa Helena Breccia zone at Borralha has been partially mined by small, shallow open pits in areas of more extensive tungsten-bearing quartz veins. Other tungsten veins have been scavenged over the years, often by "apanhistas" or illegal miners, and all mining ceased in 1985 as a result of world-wide low tungsten prices.
Highlights of the programme included:
  • 118 metre intersection in BO 8A assaying 0.29% WO3 (57m to 175m) and including 91 metre intersection assaying 0.31% WO3 (84m to 175m)
  • One of the best tungsten drill results ever reported from surface
  • 5 of the 6 drill holes ended within the boundaries of the breccia
  • A higher grade zone located in the centre of the breccia is open to the north and south and at depth to the east
  • Early indications show that the mineralized breccia may be at least 575 metres in length, over 150 metres in width and open to depth of over 200m from surface

Hole BO 8A, located directly in the middle of the Santa Helena body, returned a long intercept, of breccia starting at 2 metres, of which 118 metres from 57 m to 175 m averaged 0.29% WO3.

Hole ID Intercept - Metres Intercept %
WO3
From To Total
BO 5 21 117 96 0.14
      including 54 117 63 0.20
      including 88 117 29 0.27
BO 6 36 112 76 0.09
      including 69 89 20 0.14
and 97 112 15 0.06
BO 7 108 175 67 0.08
      including 108 123 15 0.13
and 128 142 14 0.15
and 158 175 17 0.08
BO 8A 57 175 118 0.29
      including 84 175 91 0.32
BO 9 85 93 8 0.27
and 188 199 11 0.10
BO 10 39 53 14 0.05
and 85 91 6 0.14
and 107 125 18 0.16
  152 171 19 0.07

Assay intercept widths may not be true widths, which cannot as yet be determined, as the shape and size of the mineralized breccia zones has not been determined. Tungsten analyses were performed by ALS Minerals laboratory, an accredited and internationally used firm in Vancouver, Canada using standard ME-XRF05 and ME-MS85 assay techniques for assays over 0.05% WO3..Hole BO 5, which was release July 23, 2014, was re-assayed using the above tungsten analyses, which are considered to be more accurate. QA/QC procedures included standards blanks and duplicates and accuracy and reproducibility are good. Intercepts were estimated with an arbitrary 0.50% WO3 cut-off grade.

The Santa Helena Breccia is exposed at surface and detailed historical underground mapping and detailed surface geological mapping indicates that the mineralized breccia may be at least 575 metres in length, over 150 metres in width and open to a depth of over 200 meters. There are numerous surface workings, 3 shallow open pits, and a series of underground mining tunnels, mine shafts and adits located within the breccia body. Earlier in the exploration program, trenching at the south end of the breccia exposed additional mineralization.


Figure 1. 3D Block Model of Santa Helena Breccia with drill locations and a higher grade mineralized trend shown

Tungsten mineralization in the form of wolframite is disseminated throughout the breccia and includes a higher grade mineralized trend in the center. This higher grade trend is open for expansion. No drill holes reached the eastern margin of the breccia. In addition, the breccia appears to be continuing at depth; however further drilling will be required to fully understand the true dimensions of the St. Helena Breccia and its mineralized zones. Due to the size and scope of the Santa Helena Breccia, further drilling will be required before preparation of a resource estimate. The next drilling campaign is currently being planned and is expected to start mid-2015.


Figure 2. Santa Helena Breccia Completed Drilling

Blackheath also drilled two initial holes BO 3 and BO 4 which did not intersect the Santa Helena Breccia, due to the dip of the contact of the breccia body with adjacent granitic host rocks and the inclination of the drill hole. Nonetheless, these two drill holes also intersected intermittent tungsten mineralization, which further increases management's belief in the Borralha Tungsten Project and the potential for further tungsten mineralization throughout the 127 km² mining concession. Hole BO 3 had intermittent anomalous WO3 between 15 and 61 metres and Hole BO 4 intersected 19 metres of 0.06% WO3 from 3 to 22 metres. Both holes were drilled at an inclination of 60o.


Santa Helena Breccia Trenching

Six trenches were excavated across the southern portion of the surface of the Santa Helena Breccia zone at Borralha. Results are encouraging and included 20 metres with a grade of 0.33 % WO3 (tungsten trioxide) including 5 metres of 1.09% WO3.

Santa Helena Breccia Sector - Trenches 1-6



The Santa Helena Breccia zone at Borralha, which has never been drilled, has been partially mined by open pits in areas of more extensive tungsten-bearing quartz veins. Other tungsten veins have been scavenged over the years, often by "apanhistas" or illegal miners, and all mining ceased in 1985 as a result of world-wide low tungsten prices. The breccia body is over 500 meters in length, 200 meters wide at the south end and open to an unknown depth.

The goal of the initial trenching program, in the Santa Helena Breccia, was to assess the area outside the partially mined open pits prior to commencing a drill program. Six trenches were excavated and, while it was not possible to recover samples from most of the previously scavenged surface workings, trenching results outside these workings are encouraging and showed extensive tungsten mineralization at surface in the breccia. The trenches were dug with a backhoe, cleaned and then the bedrock was sampled using a hand held diamond saw to cut a channel sample along their length of the trench.

Five trenches have widths and grades of potential economic interest, subject to further work. Mineralization of disseminated wolframite occurred in all of the trenches in the breccia and appears to be concentrated in some zones. Trenching results included the following among others of lower value. (A general cut-off grade of 0.05% WO3 has been used)

Sample From (m) To (m) Trench Width (m) WO3 %
Trench T1 (all samples) 0 100 100 0.13
     including 75 95 20 0.33
     including 85 90 5 1.09
Trench T2 0 5 5 0.23
and 120 125 5 0.27
Trench T4 35 85 50 0.10
     including 35 65 30 0.14
Trench T5 55 110 55 0.14
     including 55 65 10 0.41
and including 85 90 5 0.24
and including 105 110 5 0.33
Trench T6 0 50 50 0.10
     including 0 25 25 0.13

Trench 3 showed anomalous values less than 0.05% WO3


The Borralha property has been optioned to Blackheath by Mineralia -- Minas, Geotecnia e Construcoes, Lda., which holds the property through an exploration concession granted by the Government of Portugal. The concession is granted for an initial period of two years renewable for a further three years in one year increments, after which it may be converted into a preliminary exploitation licence and a final exploitation licence successively. Under the terms of the agreement to earn a 100% interest, Blackheath will undertake to fulfill the terms of the concession, including staged minimum exploration expenditures totalling €980,000 over five years, and to pay Mineralia €25,000 upon execution of a definitive agreement, a further €100,000 upon the grant of a preliminary exploitation licence and a further €1 million upon mine production and the grant of a final exploitation licence.