Stages of Exploration
British Lithium is continuing to refine our understanding of enriched lithium granites in the United Kingdom through responsible exploration. At our Cornwall project site, geological exploration has followed a sequence of multidisciplinary activities: research, reconnaissance, discovery, targeted prospecting and RC drilling.
Subsequent stages of exploration continue to quantify and qualify our exploration targets through additional diamond drilling and sample collection for detailed mineralogical studies. British Lithium Limited is proud of our stringent Quality Control/Quality Assurance protocol, ensuring our various sources of exploration data are validated and integrated to generate 3D models for improved interpretation and predictive targeting.
Based on our exploration, we have made a significant discovery of hard rock lithium mineralisation.
Research & Reconnaissance
Initial exploration commenced with a survey of existing literature, examination of aerial photographs and satellite imagery alongside acquisition of geophysical data and geological maps of prospective regions. This research informed our understanding of the stratigraphic setting and structural architecture of the prospect, with previous data and lithium enrichment theories incorporated into the model.
Using helicopters and exploration vehicles, British Lithium has collected a number of field samples with additional samples obtained from various museums and the British Geological Society. The samples were logged and sent for chemical analysis. Topography data was compiled from regional LiDAR and complemented with targeted UAV Stereoautograph terrain modelling (Figure 1).
Remote Sensing and Geophysics
Remote Sensing is the process of obtaining information on the physical characteristics of an area through measurement of a range of different properties from a distance. Sensors used to obtain these data can be mounted on satellites, aircraft or vehicles. In exploration, remote sending can include the use of aerial photographs, satellite imagery and airborne geophysical data to delineate deposits and structures that control them.
At British Lithium we have utilised regional radiometric, magnetic and gravity data, to draw conclusions about concealed geology.
For example, Radiometric Spectrography interrogates ratio calculations of radiometric components: K, eU and eTh to identify anomalous areas of granitic alteration. The natural decay products of potassium (K), uranium (U) and thorium (Th) vary across different granite lithologies in SW England and facilitates delineation of prospective outcrops (Figure 3).
British Lithium uterlisied the Tellus South West airborne geophysical data acquired in 2013, comprising of a high resolution magnetic/magnetic gradient survey combined with a multichannel (256 channel) radiometric survey.
An anomaly in the Remote Sensing and Geophysics data is a significant departure from the normal pattern of background values which may indicates the possible existence of mineralization and allows for the demarcation and ranking of targets for which prospecting can occur.
Trenching and Channelling Sampling
Where mineralisation occurs close to surface, trenching can be utilised to obtain samples, help establish structural controls and delineate the potential resource (Figure 4). This is a cost-effective method compared to drilling. British Lithium excavated a number of exploratory trenches through predefined targets to access mineralisation. Channels were then cut into the rock so continuous representative samples could be collected, structures such as faults and vein systems recorded and lithological variation noted (Figure 5).
Representative samples were obtained at 1m intervals across the trenches before being dried and crushed to -2 mm (Figure 6). After splitting, 200 g aliquots were dispatched for geochemical analysis by ICP, XRF assay as well as other tests such QEM an XRD. All trench data, including lithological variation, structures and geochemical data have been incorporated into a central database in order to formulate a model of mineralisation.
Initial Drilling (Phase 1)
The purpose of initial drilling was to confirm and validate anomalies in data and to establish the extent of the exploration target at depth.
In Q2 of 2019, British Lithium successfully used reverse circulation drilling as a cost-effective drilling program to support resource validation (Figure 7). The programme consisted of 6 holes drilled by a Comacchio MC900P reverse circulation rig mounted on steel track crawler with a Progradex EL350 sampler and was the first ever lithium exploration drilling program in the UK. Rigorous QA/QC procedures were documented and followed to ensure sample representivity and quality. All samples produced were bagged at site and transported to the British Lithium sample preparation facility in Roche, Cornwall, prior to geochemical analysis (Figures 8, 9).
Wardell Armstrong International performed an independent review of the RC drilling program protocol and quality control and assurance. They concluded the drilling programme generated high quality data across all intervals and all drill holes.
The initial phase 1 drilling campaign was successful in confirming the existence of lithium mineralisation from surface. Based on surface sampling, trenching, logging, and geophysical and drilling data, British Lithium prepared detailed cross-sections, longitudinal vertical sections, level plans, 3D orebody modelling, resource, and target estimation.
Down Hole Logs
To extract the most value from the drill programmes, British Lithium Limited has successfully conducted geophysical surveys of selected drill holes measuring the physical properties of the rocks in situ. These data enhance our lithological and structural understanding of the mineralisation (Figures 10, 11) through delineation of lithological features and structures that will impact the resource model.
Phase Two Diamond Drilling
British Lithium is embarking on a diamond drilling program to further delineate the mineralisation and to provide whole core samples for future lithological classification and structural information. As of 4th of December 2019, British Lithium has successfully completed the 1st diamond hole to a depth of 350m.
Objectives of the diamond drilling program are as follows:
- Establish for the extent of lithium mineralisation extension at depth. The existing RC holes ended at 200 m, still within mineralisation and so the depth of mineralisation is unknown.
- Provide core for determination of moisture content and density data over the depth tested. Bulk density data is a key factor of a resource estimate as it converts the volume of rock to tonnes.
- Verify the data generated by the RC program by twining two of the 6 RC holes. These data will be utilised by the independent geologist to declare our maiden JORC Mineral Resource Estimate. Verification will compare assay values between the twin holes for comparable meters and seek to understand the cause(s) of any difference.
- Show the validity of using the cost-effective RC method on this deposit to facilitate drilling method for the majority of resource drilling.
- Conduct detailed lithological, geotechnical and structural logging of the lithium mineralisation.
- A portion of the core samples can be used for metallurgical testwork. By using core samples from varying depth representative samples relating to various stages of the mine plan can be performed.