Santa Comba Tungsten and Tin Project
The Santa Comba tungsten and tin project is located in the Varilongo granitic massif. The host mineralisation has dimensions of approximately 8km in the north-south direction and approximately 1.5km in the east-west direction. The elongated geometry of the massif trends 005-010° which is in concordance with the main regional structures. The intrusive body is hosted by metamorphic rocks corresponding to Santiago Unit, one of the Basal Units of Ordenes Allochthon Complex, which is part of Galicia-Trás-os-Montes Zone (GTMZ), included itself in the Iberian Massif of the Variscan Orogen (Figure 2). The metamorphic rocks are comprised of schists, paragneisses and felsic orthogneisses.
The massif (Figure 2) is not homogeneous and is composed of at least three main, well defined granite types, known as two mica exogranite (EXG), biotitic exogranite (BEXG) and endogranite (ENG) in keeping with the terminology of previous explorers. These facies or lithologic types include some internal variations or sub-facies and there are also some varieties with intermediate compositions. The endogranite lithology has been the focus of Rafaella’s 2019-2020 and 2021 drilling activities and hosts widespread disseminated tungsten and tin mineralisation. The predominant tungsten mineral is wolframite with minor scheelite. The tin mineral is ubiquitously cassiterite.
All granite types are crosscut by abundant quartz veins parallel or subparallel to the regional foliation of the massif (005-010°). It is these veins that host the tungsten-tin mineralisation which was the primary focus of historical mining activities throughout the massif. The veins are more prevalent in the southernmost area of the massif and it is here where extensive underground mining activities occurred periodically between the 1940’s and 1980’s. Cutting the massif there is also an important set of fractures and faults. Highlighting among them there are some NW-SE faults which frequently induct variable kaolin alteration, sufficiently strong in some areas that they have been economically exploited in the past.
Advanced Pre-feasibility Study (PFS)
On June 20, 2022, the Company announced the results of an Advanced pre-feasibility study. The Advanced PFS was prepared in accordance with JORC 2012 by Consultores Independientes en Gestión de Recursos Naturales, S.A. (CRN) and follows the 42% increase in the Mineral Resource Estimate reported in August 2021 (after the 2021 drill campaign) and test work that showed improved metallurgical recoveries from Santa Comba project ores in January 2022.
Two main cases have been run:
- the Management Case (which incorporates 445kt of Inferred Resources being 5.6% of total production) and
- the Ore Reserves Case which has been used to generate the assignment of Ore Reserves. All numbers that follow are those generated from the Ore Reserves Case, unless specifically stated otherwise.
The key economic outputs are summarized in Table 1.
TABLE 1: COMPARATION BETWEEN PRODUCTION RESOURCE SCENARIOS
*Management Case includes 5.5% Inferred Resources.
Cautionary Statement There is a low level of geological confidence associated with inferred mineral resources and there is no certainty that further exploration work will result in the determination of indicated mineral resources or that the production target itself will be realised.
TABLE 2: PROJECT OVERVIEW (MANAGEMENT RESERVES CASE)
Key assumptions and Operational Parameters are detailed in Table 2.
Ore Reserves are supported by a Resources Block model developed by Wardell Armstrong International (WAI) and pit designs. Ore Reserves have been assigned to the Project as follows:
TABLE 1: RESERVES ESTIMATE MAY 2022
TABLE 1: TOTAL MINERAL RESOURCES ESTIMATE FOR SANTA COMBA - AUGUST 2021
Underground JORC Mineral Resource Estimate
Table 2 shows the details of the underground mineral resource estimate (‘UG MRE’) for Santa Comba, including the Zone Mina Carmen North updated by Rafaella as of February 2022 and the unchanged UG MRE of Zone Mina Carmen South, dated August, 2016.
TABLE 2: UG MINERAL RESOURCE ESTIMATE FOR MINA CARMEN, SANTA COMBA - FEBRUARY 2022
UG Inferred: Cut-off = 0.53% WO3
Rounding as required by reporting guidelines may result in apparent summation differences between tonnes, grade and contained metal content. Where these occur, they are not considered material.
TABLE 3: UG MRE FOR ZONE MINA CARMEN NORTH AT DIFFERENT CUT-OFF GRADES - FEBRUARY 2022
Underground Exploration Target
Rafaella has delineated substantial Exploration Targets for both Mina Carmen North and Mina Carmen South, which would require a drill program of between 3,000m to 4,000m for generating Inferred resources with the objective of 1Mt at 1.0% (WO3 + Sn) combined (table 3).