Lanka Graphite : maps new vein graphite targets

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24 October 2016

• Reconnaissance geological mapping has confirmed further locations of historical workings and identified structural targets for vein graphite deposits in two of Lanka Graphite's licences in southAwestern Sri Lanka
• Very Low Frequency (VLF) Electromagnetic (EM) surveys have identified zones of elevated conductance below and between old shafts and adits historically mined for vein graphite
• VLF anomalies extend away from known occurrences of vein graphite, suggesting strike extensions
• Results of this latest VLF survey will underpin a proposed second phase of detailed geophysical surveying.

Lanka Graphite Limited (ASX: LGR) is pleased to announce the results from an ongoing VLF geophysical survey and geological mapping exercise being undertaken over its Exploration Licences in southwestern Sri Lanka.

Geological mapping has identified old pits, shafts and adits on Exploration Licences (EL) EL236 and

237. The mapping also highlighted structural and lithological trends that may be related to vein graphite mineralisation.

The VLF survey targeted three grids in EL236 and two grids in EL237 (Error! Reference source not found.) where there are historical graphite workings. The VLF survey results suggest the presence of graphite mineralisation between and beyond the extent of the mine workings, indicating that the mineralisation may extend beyond historical mining areas. Several of the conductors detected in the VLF surveys have no historical mine workings, and may be related to untested graphite mineralisation under cover.

Sri Lanka has a long history of graphite mining dating back to the early 1800s with peak production in the first two decades of the twentieth century, reaching 33,410 long tons in 1916.

Sri Lankan graphite occurs predominantly as veins ranging in thickness from veinlets less than 1 mm thick to veins over 1 m thick. The veins are often zoned and contain more than one type of graphite

e.g. flaky, needle or massive, related to the depositional conditions. The veins pinch and swell and

also can end abruptly and are sometimes of limited extent and can be better described as lenses. In some case the veins can occur in clusters.

Vein graphite mineralisation is commonly associated with pegmatites and vein quartz, both related to tensional zones of open space in fold hinges and cross cutting structures. The graphite veins follow linear, subvertical, zones aligned with the axes of antiforms and is considered to have been derived from CO2 in late hydrothermal fluids, produced during metamorphism.

Graphite veins may also be located in secondary fractures at steep angles to the strike of the antiformal hinge zones, although not all such fractures are so infilled. These types of secondary fracture veins can form the bulk of the graphite resource in a deposit in Sri Lanka.

Given that Sri Lanka was previously a major world supplier of highquality vein graphite, extensive mining and prospecting for graphite occurred in the country over the past two centuries. Old shafts, adits and prospecting pits are therefore a common starting point for present day exploration.

Figure 1. Location of Lanka's tenements in southwestern Sri Lanka.

Reconnaissance geological mapping has been completed by GSMB over portions of EL236 and EL

237. Several historical graphite pits, shafts and adits were identified and mapped; an example of the historical workings is shown in Figure 3. The distribution of the graphite occurrences together with geological information will assist in prioritising targets for followup.

EL236 Zone 3 Dodangoda area, Wallawita

Geological mapping in the three grids 03, 31 and 35 of EL236 identified charnockitic gneiss, garnet sillimanite schist and garnet hornblende biotite gneiss. Structural mapping in grid 03 showed that the predominant joint direction is NNESSW and NESW, while structural mapping in grids 31 and 35 indicated that the main joint direction is EW and NS.

An abandoned graphite mine field was observed in the Ridiwita area, where several vertical pits were identified. Most of them have been filled with sediments and covered with vegetation, however it was possible to find needletype graphite particles in the area (Figure 1).

EL237 Zone 2 GonagalaRuwanella area

Geologically, the study area is interpreted to be in the Wanni Complex, close to the marginal zone of the Highland Complex. The mapped grids are mainly composed of paragneisses including garnet sillimanite biotite gneiss, charnockitic gneiss, granitoid gneiss, and garnetiferous quartzofeldspathic gneiss. According to government geological mapping, the grid straddles the Gonagala Antiform, which is flanked by northsouth trending shear zones (Figure 2). Old pits and shafts were mapped near the eastern part of the grids, near the antiformal axis.

The grids mapped in EL237 are located in the Ruwanwella division of the Kegalle District in Sabaragamuwa province, where several abandoned graphite pits, adits and shaft were identified (Table 1).

Table 1. Location of old workings, Ruwanella area

Figure 1. Old working and vein needle graphite fragments in the Ridiwita area, EL236

Figure 2. Government geology map of the Ruwanella area, EL237, showing antiformal and synformal

structures