The following information is an extract from The Achmmach Tin Project Small Start Option Definitive Feasibility Study Report completed in 2016.

Key Points

The following key points apply to the Achmmach deposit mineralisation:

  • Tin mineralisation comprises fine-grained cassiterite with associated minor sulphide minerals in a tourmalinised sandstone / siltstone shale host;
  • A robust and unbiased technique for tourmaline mapping, based on the potassium content as a proxy, was established and used for the latest geological interpretations in 2013;
  • It has become apparent from tightly spaced drilling interpretations that sub-vertical east –west striking tourmaline zones co-exist with oblique north dipping ones;
  • The significant increase in drillhole data has enabled the classification of the entire Meknès Trend as a Measured and Indicated Resource translating into high confidence in geometry and continuity of the mineralisation;
  • Geology:
    • The Achmmach tin mineralisation is an epigenetic vein-stockwork-breccia type deposit associated with a strongly boron-enriched paleo-hydrothermal system. It is interpreted as being hosted by two cross-cutting swarms of tourmaline-altered zones; a series of east-west striking sub-vertical zones described as “feeders” and a stacked series of oblique gently to steeply north-dipping “branches”;
    • The 1.6 km strike extent of the mineralisation system is entirely hosted by sequences of folded and metamorphosed shales and sandstones. The lodes form a 300 m wide array across strike with individual lode structures ranging from a metre up to 30 m wide. Tin mineralisation occurs primarily as breccia infill and quartz-cassiterite veins and has been defined in diamond drill holes to a vertical depth of approximately 600 m below natural surface (to approximately 600 mRL);
    • The bulk of the known mineralisation intersected by the current drilling occurs between 920 mRL and 800 mRL below surface; and
    • The deposit is open at depth and along strike.

Local Geology

The Achmmach tin deposits occur within metamorphosed shales, siltstones and sandstones of Lower Carboniferous (Mississippian) age. The metasediments occur as a flysch sequence which trends north to north-north-east (UTM) for at least 20 km. Shale is the dominant rock type. Sandstone units are up to several metres thick but are generally less than 30 cm thick, with the thicker sandstone units being restricted to the western part of the project area.

Subsequent to deposition the sediments underwent substantial ductile and brittle deformation during the Variscan orogeny. Resulting bedding is commonly moderate to steeply dipping to WNW.

The Achmmach tin deposits occur within metamorphosed shales, siltstones and sandstones of Lower Carboniferous (Mississippian) age. The metasediments occur as a flysch sequence which trends north to north-north-east (UTM) for at least 20 km. Shale is the dominant rock type. Sandstone units are up to several metres thick but are generally less than 30 cm thick, with the thicker sandstone units being restricted to the western part of the project area.

Subsequent to deposition the sediments underwent substantial ductile and brittle deformation during the Variscan orogeny. Resulting bedding is commonly moderate to steeply dipping to WNW. Frequent metre-scale tight parasitic folds are observed over the project area, mostly gently plunging NNE, moderately inclined WNW and ESE-verging.

The regional trend of the strike of the host rocks is north to north-north-east. The Achmmach hill which trends 70 degrees east of north translates a change in strike explained by the occurrence of resistant tourmaline and silica-bearing structures.

The metasediments have been intruded by sub-volcanic felsic and mafic igneous rocks. The Palaeozoic sequence has been intruded by Hercynian (Upper Carboniferous-Permian) granite, which outcrops about five kilometres to the west of Achmmach. The host rocks have been overprinted by fine grained black tourmaline over a strike length of at least 1.6 km and a plan width of 200 m to 500 m. This tourmaline alteration corridor is a distinctive feature in the area mapped from the Bou-El-Jaj prospect to the south west corner of PE2912 trending NNE and across PE2912 trending ENE.

The east-west striking Sidi Addi Fault is the main structural feature at Achmmach and occurs in the northern part of the deposit.

Project Geology

Tin mineralisation at Achmmach occurs as cassiterite in quartz-cassiterite veinlets and stringers, and as disseminations. The veinlets and stringers are commonly narrow, up to a few millimetres thick. Thicknesses up to a few centimetres occur locally. The host rocks were altered by black tourmaline and white quartz before the introduction of cassiterite as stringers and veinlets. Tin presents as disseminations in black tourmaline and as infill to some breccias.

Taylor (2009) suggested a paragenesis, the stages of which most relevant to the tin mineralisation are:

  • Tourmaline II and Quartz II occur together and rock containing moderate to strong Tourmaline II mineralisation is host to the tin mineralisation; and
  • Quartz-cassiterite ± arsenopyrite, pyrite and chlorite mineralisation contains the tin.

Kasbah geologists have noted a general relationship between tin grades and the mode of occurrence of cassiterite as outlined in Table 3 1.

Table 3 1: Cassiterite Occurrence at Achmmach

Grade Range Modes of Occurrence of Cassiterite
Up to about 0.5% Sn Quartz-cassiterite +/- sulphide stringers and veinlets not necessarily in tourmaline; and
Quartz-cassiterite stringers and veinlets in tourmaline
About 0.5% to about 2% Sn As above plus disseminated cassiterite in the interstices of tourmaline
Over about 2% Sn As above plus wider and higher grade quartz-cassiterite veinlets and veins or cassiterite as infill matrix of breccia

The Achmmach Tin Project comprises mineralised envelopes or lodes, which are known over a strike length exceeding 1.6 km. Close-spaced drilling has enable the identification of east-west striking sub-vertical tourmaline envelopes described as “feeders” and gently to steeply north dipping “branches”. The tourmaline envelopes have been defined by drilling over a vertical interval of approximately 600 m. The envelopes range from a few metres to over 30 m thick. The mineralised envelopes appear to be relatively continuous in plan, reflecting the continuity of the tourmaline alteration mapped at the surface.

The occurrence and spatial distribution of the cassiterite veinlets in the mineralised envelopes dictates the distribution of tin which needs to be taken into account during grade interpolation. In summary, there are several features of the tin mineralisation which are important to the resource estimate:

  • The mineralised envelopes are primarily tourmaline-rich envelopes. The envelopes contain the bulk of the tin in the form of quartz-cassiterite veinlets. As with other hydrothermal tin deposits, leakage of tin occurs beyond the envelopes as country rock disseminations;\
  • Quartz-cassiterite veinlets are not ubiquitous in tourmaline envelopes. There are parts of the envelopes that are not mineralised with tin. The current geological interpretation does not include any constraint on the location of tin within these envelopes; and
  • The quartz-cassiterite veinlets are steeply dipping, while the mineralised envelopes are moderate to steeply dipping.


BRPM Estimate

In 2002, BRPM (subsequently ONHYM) evaluated a resource for Achmmach by completing a programme of 29 diamond drill holes and bulk sampling from an underground exploration adit on the 890mRL level.

Using this data, ONHYM produced an unclassified resource estimate of 9.57 Mt containing 1.09% Sn at a cut-off grade of 0.50%. This estimate does not comply with the JORC guidelines and therefore was not classified as Mineral Resources under this code.

As a result, additional resource definition work was undertaken by Kasbah with the aim of defining a JORC-compliant resources.

The last JORC 2012 compliant resource upgrade revised by QG in November 2014 underpins this Study. It is based on the completion of 270 diamond drill holes totalling 102,905 m. The resource estimate, based on a cut-off grade of 0.50% Sn. Table 3 2 shows the breakdown of the prevailing Mineral Resource at Achmmach.

The classification of the entire resource of the Meknès Trend falls within Measured and Indicated categories.

Table 3 2: Meknès Trend Mineral Resource Estimate – (QG, November 2014)

(Estimated as at 24 November 2014)

Target Cut-off
Tin Grade
Sn Metal
Meknès Trend 0.50% 1.6 1.0 16.1
Sidi Addi Trend (Western Zone ) 0.50% - - -
Subtotal   1.6 1.0 16.1
Meknès Trend 0.50% 14.6 0.85 123.1
Sidi Addi Trend (Western Zone ) 0.50% 0.3 1.25 4.2
Subtotal   13.3 0.8 111.2
Meknès Trend 0.50% 14.6 0.85 123.1
Sidi Addi Trend (Western Zone ) 0.50% 0.3 1.25 4.2
Grand Total   14.9 0.85 127.3


The Achmmach Project is covered by two exploitation permits (PE 2912 and PE 193172), covering a total area of 32 km². Under the terms of the agreement with ONHYM, Kasbah acquired 100% of the Achmmach Project and its permits during 2012, after having completed a Scoping Study on the project in late 2010.

ATS as the Moroccan Joint Venture company now holds 100% of the permits.

Regional Geology

The Achmmach deposit is located in the Paleozoic Central Massif of the Western Meseta Domain, which itself is part of the larger Variscan (Hercynian) Orogenic belt. This Hercynian belt is developed around the 2 Ga-old continental nucleus of the West African Craton through repeated oceanic closures and collisional orogenic events from 460-420 Ma (Caledonian) to 360-300 Ma (Hercynian). The Atlas-Meseta domain is strongly deformed, weakly metamorphosed and intruded by varied granite massifs.

Figure 3 1 illustrates the Variscan orogenic belt.

Reconstruction of the Variscan Orogenic Belt

Figure 3 1: Reconstruction of the Variscan Orogenic Belt (380-260 Ma) with Locations of Major Tin Deposits

The Palaeozoic terranes of the Meseta Domain are widely covered by Mesozoic-Cenozoic formations and as a result, are exposed as isolated massifs.  The Western Meseta is composed from north to south of the Central, Rehamna and Jbilet massifs.  It is further subdivided into the Western Central Meseta and Eastern Central Meseta by the Smaala-Oulmès Fault Zone and the NE-trending Moulay Bou- Azza Fault.

The Achmmach Deposit is located about 2 km east of the Moulay Bou Azza fault in the Eastern Central Meseta as shown in Figure 3 2.

Moroccan Geologic Domains

Figure 3 2: Moroccan Geologic Domains

Three main Hercynian granites outcrop within the Central Massif; the Zaer Granite in the west, the Oulmès granite in the central-east, and the Ment Granite in the east.  The Oulmès Granite hosts the El Karit Tin Deposit where tin mineralisation occurs as cassiterite in small lensoid quartz veins over an area nearly 5 km long and 250-500 m wide.  Tin-tungsten mineralisation is also associated with the Zaer Granite and the Ment Granite.

Early regional mapping (Termier, 1936) identified a 15 km x 8 km contact metamorphic aureole covering an area extending from El Hammam to Achmmach, suggesting the presence of a large buried granite.  However, no large intrusives outcrop within the Achmmach deposit area, only a clustered occurrence of small monzogranite outcrops in the Oued Beht (River), 5 km west of Achmmach with associated tin-tungsten bearing skarns.

The Achmmach deposit is located within the turbiditic (flysch) deposits of the Namurian Fourhal Formation.  The host rocks continue to the south west as shown in Figure 3 3.

Achmmach Regional Geology

Figure 3 3: Achmmach Regional Geology (and Kasbah / ATS Permits)


Host Rocks

The Fourhal Formation comprises a series of folded, sheared and weakly metamorphosed shales (pelites) and sandstones (psammites) of Lower Carboniferous (Visean-Serpukhovian) age. These meta-sediments are interpreted as a series of turbidites deposited in the Fourhal Basin. Generally found in outcrop and drill core, shales, siltstones and sandstones are interbedded on centimetre to decimetre scale as illustrated in Figure 3 4.

Typical Interbedded Sandstones and Shales at Achmmach

Figure 3 4: Typical Interbedded Sandstones and Shales at Achmmach

The meta-sediments have been intruded by number of sills and dykes with metric to first decametric width.  Their composition varies from basic - intermediate (dolerite, gabbro and microdiorite) to felsic (monzogranite, microgranite and rhyolite).  The strike continuity of the intrusives varies from tens of metres to more than a kilometre.  The majority of the intrusives are interpreted as being pre-mineralisation as commonly they are tourmaline-altered and carry tin mineralisation.  The mafic types are clearly more abundant in the Eastern segments of the deposit, while in the Central and Western parts one felsic and one mafic intrusive could be consistently traced.  The felsic intrusive (monzogranite) is of particular interest as it commonly defines the hangingwall of high-grade mineralisation in this area.


The rocks at Achmmach have experienced substantial repeated deformation during the Variscan Orogeny period that led to the closure of the Fourhal basin, folding and faulting of the deposited sediments and the intrusion of various suites of igneous rocks.

Bedding in the area is normally moderate to steeply dipping to WNW with some local variations. Numerous metre-scale tight parasitic folds are identified. Vergence is generally to ESE while fold axes are gently plunging NNE. Asymmetries of the limbs of the small folds indicate that Achmmach is probably located on the western limb of a major anticline (Compston, 2011). Commonly the folds hinges are sheared and thrusted to the ESE along the axial planar cleavages. Syntectonic milky quartz veins are abundant in these zones. Ubiquitous across the deposit is a subvertical E-W to WSW striking spaced fracture cleavage.

It is argued that this development is related to a transition to transpressional deformation conditions. These structures have a major control on the distribution of the tourmaline alteration and subsequently the tin and sulphide mineralisation.

Late brittle faulting has limited extent at Achmmach. It is restricted basically to the ENE-striking, North dipping Sidi Addi normal/dextral wrench fault and several shorter range cataclastite zones. These have experienced only minor displacement, as no major off-set of the principal structures has been recorded.


The rocks at Achmmach bear signs of extensive modification by epigenetic hydrothermal fluids that are believed to be related to deeper granitic intrusions. The large volume of the hydrothermally altered rocks is indicative of a large paleo-hydrothermal fluid system. These fluids are thought to have intermittently released into the higher crust with evolving chemical and physical properties responsible for the alteration halo and subsequent mineralisation. Two main types of alteration are distinguished at Achmmach:

  • Quartz-Sericite-Chlorite+/-Pyrite Alteration
    This is the earliest alteration assemblage. It is a fairly widespread, pervasive type that appears to develop preferentially along faults, cleavages and shear zones. This type however can propagate along bedding planes far away from its conduits. Minerals are fine grained and give the rock a specific green-yellowish coloration that is better discernible in core than in oxidized surface outcrop.
  • Tourmaline-Silica Alteration
    The most prominent features of the deposit visible on surface are the extensive tourmaline lodes and breccias locally of such intensity that the whole rock packages could be regarded as tourmalinites (rock with >40% tourmaline). This type forms two sub-parallel trends on the Meknès Trend and the Sidi Addi Trend, which extend for nearly 2 000 m across the project in an ENE orientation in a 500 m wide zone.

Figure 3 5 below illustrates these alteration types.

This alteration is also strongly structurally controlled, developing along the steep E-W fracture cleavage which also preferentially invades shear zones, fold hinges or advances along bedding, and locally forms extensive hydraulic breccias. The tourmaline alteration acts as a host to the main quartz cassiterite veins and breccias which contain the bulk of the tin in the deposit. In general the absence of tourmaline alteration suggests absence of significant tin. However, the presence of tourmaline is no guarantee of tin mineralisation.

General Geology of the Achmmach Deposit

Figure 3 5: General Geology of the Achmmach Deposit and Alteration Zones

Two sub-types of tourmaline alteration have been identified during microscopic studies but are not easily distinguishable with the naked eye:

  • Tourmaline I 
    Composed of brownish early stage pervasive fine grained tourmaline (5 20 µm) only.  This type passively overprints shear zones, cleavages, fold hinges and also advances along bedding surfaces.
  • Tourmaline II 
    Dark blue-black (often zoned), coarser grained (50 100 µm) and invariably in association with fine quartz.  It overprints the pre-existing associations along brittle fractures, locally forming forcefully emplaced tourmaline-quartz cemented breccia zones and pockets.


Similar to many other tin provinces in the world, the mineralisation stage at Achmmach is a natural part of the evolution of the hydrothermal system forming around specific fractionated granitoid plutons.  Taylor (2008, 2009) summarized the progressive changes in the mineral paragenesis from the earliest to the latest stages of development of the system as shown in Table 3 3 below.

The stages that are most relevant to the formation of the deposit are:

  • Tourmaline II - Quartz 
    Alteration that provides the critical host rock preparation as illustrated by Figure 3 6; and
  • Quartz-cassiterite ± tourmaline; arsenopyrite, pyrite and chlorite

Being an event that carries the tin-chloride complexes that deposit the main volume of cassiterite in suitable structures.

Table 3 3: Achmmach Alteration/Mineralisation Paragenesis Modified from Taylor 2008, 2009

Timing Stage Description Comment
Early Pre-hydrothermal Milky white quartz ± pyrite: Syntectonic hydrostatic veins Common
  Hydrothermal sericite alteration Sericite-quartz±chlorite±pyrite: broad pervasive zones Prolific
  Hydrothermal quartz-tourmaline mineralisation

Tourmaline I: brown, pervasive alteration along shear fabrics and bedding Prolific
Tourmaline II+quartz:  dark blue, pervasive + new fractures and breccia infill Common
  Hydrothermal quartz-metal mineralisation Quartz-arsenopyrite±tourmaline: stringers, veinlets and veins. Uncommon
Quartz-cassiterite±tourmaline, arsenopyrite, pyrite and chlorite: stringers, veinlets, veins, breccia infills and disseminations. Common
Cassiterite ± pyrrhotite ±chalcopyrite±pyrite, ±arsenopyrite: stringers and veinlets. Uncommon
Pyrite±sphalerite±galena±antimonite±stannite: stringers and veinlets. Uncommon
  Late hydrothermal mineralisation Quartz III±carbonate Sporadic
Carbonate-quartz Ubiquitous
Quartz IV±pyrite Rare
Late Post-hydrothermal? alteration Pyrite-clay Rare

The mineralisation is developed predominantly within the intense tourmaline-silica altered meta-sediments commonly referred to as “lodes”.  It occurs mostly as veinlets, and cm wide veins.  Disseminations within the acicular Tourmaline II or the porous sandstone beds are locally important.

High grade ore shoots are normally associated with dense fracture / stockwork arrays, bigger and high frequency sheeted veins reaching up to few cm thickness, and also hydraulic breccias as shown in Figure 3 7.

Black Tourmaline II

Figure 3 6: Black Tourmaline II –Quartz Alteration and Milky Quartz I

Achmmach geology

Figure 3-7: Fine grained cassiterite (brownish) as vein infill and dissemination along the edges with late stage cross cutting carbonate (whitish) veins

The bulk of tin mineralisation occurs as cassiterite (SnO2 – S.G. 6.80-7.10, 78.6% Sn).  Although stannite (Cu2FeSnS4) occurs in some veins, it is not a significant mineral in the deposit.  Cassiterite is usually relatively fine grained (50 µm to 120 µm) with a brownish-grey colour.  It is relatively pure in composition and does not carry significant trace elements (e.g. In, Ga, Ta or Nb).

Table 3-4 describes the mode of occurrence of cassiterite in terms of grade.

At Achmmach it appears that the main stages of mineralisation are superimposed on one another (telescoping effect) and as such no obvious zonation is apparent.  Each stage exhibits a vertical extent of several hundred metres, and any zonal effects will only become obvious at the upper and lower extremities of the system.

Table 3-4: Tin Grades and Modes of Occurrence of Cassiterite at Meknès Trend.

Grade Range Modes of Occurrence of Cassiterite
Up to about 0.5% Sn Quartz-cassiterite-sulphide stringers and veinlets not necessarily in tourmaline and
Quartz-cassiterite stringers and veinlets in tourmaline.

About 0.5% to about 2% Sn As above plus disseminated cassiterite in the interstices of tourmaline
Over about 2% Sn As above plus wider and higher grade quartz-cassiterite stringers and veinlets or cassiterite as infill support of breccia

Exploration History

By Kasbah Resources

In 2005, Kasbah commenced the acquisition process of the Achmmach Tin Project from ONHYM. At first, the BRPM data package was reprocessed by Carras which led to a JORC compliant inferred resource of 2 Mt @ 1% Sn at a 0.6% Sn cut-off. Since then Kasbah, has worked on the licence alternating between surface works and drilling campaigns.

Completed surface work includes:

  • Various mapping programs of the entire hill at a scale of 1/1 000. In particular Dr D Compston of Xserv was commissioned in 2007 and 2011 to achieve first pass and follow up mapping of the Meknès and Sidi Addi Trends.
  • Soil (1 218 records on PE2912) samples were collected at a 80 m x 40 m grid spacing over the hill and at 160 m x 80 m grid elsewhere on PE2912. Rock chip (447 records on PE2912) samples were mostly gathered from tourmaline structures of the North Zone, the Eastern Zone Shallow and the Western Zone Shallow. Elsewhere on PE2912, a handheld Niton XRF analyser was used to test for mineralisation.
  • A ground magnetic survey was carried out over the Achmmach Tin Project in 2008 and 2009. Resource Potentials out of Perth, Western Australia was commissioned for the acquisition and processing of the data. A total of 310 line km was surveyed over the hill and in the surroundings of PE2912. This achieved line spacings of 50 m over the hill, progressively increasing to 100 m and 200 m further in the perimeter.

Since commencing the first drilling campaign in 2007, Kasbah employed four contractors to conduct diamond drilling over PE2912.  Diamond core was orientated whenever possible using Eazymark or Reflex ACT tools.

In parallel with the drilling programs, various consultants have been commissioned to carry out petrological and structural analysis on core.  Consultants and studies were as follows:

Roger Taylor carried out studies on the paragenesis of the Achmmach deposit in 2008 and 2009 along with petrological descriptions of samples in 2012;

Dr Toby Davis from Impel Geoscience in Perth, Western Australia (Impel) was commissioned in 2009, 2010 and 2011 to complete structural studies on orientated core; and

Dr Simon Dorling of CSA in Perth, Western Australia completed a structural study on drill sections from the Gap Zone in 2012.

Resource estimation consultants were commissioned several times between 2007 and 2013 as described in the following.

Mineral Resouce Estimates

Mining One Pty Ltd

In Q1 2012 Kasbah engaged Mining One to prepare a third JORC compliant resource estimate.  This estimate was based on diamond drilling completed from late 2010 through early 2012, which mostly consisted in covering the Gap Zone by 80 m infill sections.

The geological interpretation used as the framework for the Mining One resource estimate was completed by Kasbah’s geologists.  The envelopes shown in the middle right of Figure 3 8 capture tourmaline alteration associated with tin grade.  Alteration intensity was derived directly from logging records.  The mineralised envelopes generally dip moderately to steeply north with an average dip/dip direction of -50/350.  The mineralised envelopes appear to be relatively continuous in plan, reflecting the continuity of the tourmaline alteration mapped at the surface (Figure 3 5).  In cross-section, the mineralised envelopes have been referred to as “stacked lodes” and each envelope is separated from, and off-set to the south relative to the lode above it.

Mining One obtained the following JORC compliant Resource estimate as detailed in Table 3-6 of:

  • 5.3 Mt @ 0.8% Sn Indicated Resource, containing 42 kt tin metaI at a cut-off of 0.50% Sn; and
  • 9.3 Mt @ 1.0% Sn Inferred Resource containing 93 kt tin metaI at a cut-off of 0.50% Sn.

Drilling and Geological Model Evolution of the Meknès Trend

Figure 3 8: Drilling and Geological Model Evolution of the Meknès Trend from 2002 to 2013/09 and Successive Resource Estimations

Year Mt Grade %
kt Sn COG % Sn Inferred
Mt @ % Sn
Mt @ % Sn
Mt @ % Sn
Total drill
2002 BRPM* 9.60 1.10 105.60 0.50 0 0 0 14 258 14 258  
2006 KAS (SNC) 2.00 1.00 20.00 0.60 2.0 @ 1.0 0 0 14 258 14 258  
2008 KAS (SNC) 6.00 0.90 54.00 0.60 6.0 @ 0.9 0 0 21 854 14 258 7 596
2010 KAS (QG) 7.00 0.80 56.00 0.50 4.8 @ 0.8 2.2 @ 0.8 0 29 432 14 258 15 174
2012 KAS (M1) 14.60 0.92 135.00 0.50 9.3 @ 1.0 5.3 @ 0.8 0 53 402 14 258 39 144
2013/03 KAS (QG) 15.30 0.85 130.10 0.50 0.6 @ 0.7 14.2 @ 0.85 0.5 @ 1.2 95 930 14 258 81 672
2013/09 KAS (QG) 14.60 0.85 123.10 0.50 0 13.0 @ 0.80 1.6 @ 1.0 117 163 14 258 102 905

*Unclassified estimate

The two most recent resource estimates from QG relate to the current geological model and are described in the following.

Current Geological Model

With the infill drilling at 40 m spacing over the Gap Zone and the Meknès Eastern Zone, together with the subsequent 20 m-spaced infill drilling of 240 m of strike length from 2390 mE to 2630 mE, it became apparent that north-dipping oblique tourmaline envelopes coexist with sub vertical east west striking envelopes.

In order to create tourmaline alteration zones, Kasbah used potassium (K) as a proxy as it is progressively depleted as the intensity of tourmaline alteration increases (Barabino, internal report, 2011). As a result, tourmaline alteration envelopes associated with grade used for the latest resource estimates in 2013 are less dependent on logging data that can occasionally be subjective.

Given the above, both 2013 resource estimates interpret the Meknès Trend as being defined by several ENE-WSW striking sub-vertical mineralised structures. These sub-vertical structures described as “feeders” are the presumed conduits for the granite-emanated fluids which carry tin mineralisation. As these fluids reached higher levels, they produced tourmaline alteration haloes within the deposit and deposited tin mineralisation in favourable trap sites that pervade up and down dip from the feeders described as “branches”.

Figure 3-9 highlights examples of trap sites in the context of the current geological model.

3D Diagram Looking West of the Achmmach Geological Model

Figure 3 9: 3D Diagram Looking West of the Achmmach Geological Model Sliced at 2450m E (local grid).

Model limits

Several unknowns about the geology at Achmmach remain:

  • It is still unclear why certain tourmaline structures are associated with tin mineralisation and others are not;
  • Even if the level of prediction of tourmaline envelopes is strong in the Meknès Trend, the underlying criteria determining whether tourmaline alteration should pervade in a certain rock or not will need to be closely analysed.
  Subscribe to Email Alerts