Gakara is a high grade but low volume rare earth project and was the only African producer of rare earths when in operation. Located in Western Burundi, approximately 20km south-southeast of Bujumbura, the project benefits from good infrastructure, with road links to Dar es Salaam, Tanzania and Mombasa, Kenya.
Rainbow was granted a mining licence in March 2015, which is valid for 25 years and renewable thereafter. Rainbow has a 90% interest in the Gakara Project with a non-dilutable 10% owned by the Burundi State. The mining permit covers a large area of over 39km².
Various mining methods have been trialled by Rainbow as the team sought to evaluate the optimal mining method for a commercial-scale mine. The mineralised veins at Gakara have a high in-situ resource grade but are narrow and non-uniform in nature. Selective mechanical mining of ore delivers a grade of approximately 10% rare earth oxides, amongst the highest rare earth run of mine grades in the world. Rainbow put in place a pilot processing plant which produced a mixed rare earth concentrate of typically 54% total rare earth oxide (“TREO”). These high grades demonstrate the potential for the trial mining project to be cash generative once operations have been optimised and subject to global rare earth pricing.
In June 2021, operations at Gakara were suspended at the request of the Government of Burundi, with the majority of staff placed on suspension and short-term cash requirements minimised. Rainbow continues to engage constructively with all stakeholders to resolve the issue and allow trial mining to recommence.
Where we operate
- 39km² Mining licence, within an overall coverage area of 135km², valid until 2040
- 90% Rainbow’s interest in the Gakara Project
- High Grade
- Very high-grade ore.
- Numerous and extensive veins containing nearly pure bastnaesite and monazite minerals.
- 262-375,000 tonnes high grade veins at 7-12% TREO and 252-342,000 tonnes low grade Breccia at 1.0-1.5% TREO.
- NdPr, the critical input materials in permanent magnets, represent approximately 88% of the overall basket value.
- Simple Operation
- Veins extracted by selective mechanical mining of ore (no explosives required).
- Trial mining and processing since 2017 have demonstrated low risk, low opex mining and amenability for simple, low-cost gravity separation.
- Simple, physical separation of minerals from waste rock produces high-value rare earth concentrate of 52-56% TREO, with low levels of radioactivity.
- No complicated or hazardous chemistry required.
Geology and exploration upside
Both known mineralisation styles at Gakara (vein and breccia hosted) contain the same basket of rare earth minerals and produce an identical quality saleable concentrate. The mineralised veins are discrete and narrow, and the mineralised material separates easily from the less dense host rock which is amenable to manual digging. The veins range in thickness from a few centimetres to a few tens of centimetres. The veins have been shown to typically extend laterally for tens of metres, the longest recorded being over 80 metres, and have been observed to extend down to depths greater than 25 metres. The veins outcrop at surface on steep slopes or river incisions but are frequently under cover.
Significant amounts of exploration work have been carried out across the project area since inception, with a summary as follows:
|Pitting and trenching
|85 pits (75 at Gasagwe and 10 at Kiyenzi): 34 trenches in 8 targets
|7,956 geological observation points acquired including 1,529 RE occurrences of which 1,136 are in situ veins
|Rock grab sampling
|632 Sites Sampled And Analysed By Niton Hand-Held XRF; 150 Rock Grab Samples Analysed By ALS Chemex, South Africa
|Soil sampling (orientation survey)
|591 samples from three blocks (500m x 500m): all analysed by Niton and ALS Chemex, SA 2,906 samples from 4 geophysical grids collected and analysed by Niton only
|Ground gravity (orientation survey)
|3.6 line km on 7 selected sites
|Ground magnetic (orientation survey)
|10 line km on 7 selected sites
|Airborne geophysical survey
|High-resolution, helicopter-borne, magnetic and radiometric survey flown over 130km° area, at 50m line spacing, and comprising of a total of 2,969 line km
|Structural geology study and targeting by TECT Geological Consulting
|Structural and lithological interpretation of high-resolution geophysical data, followed by the generation of new exploration targets using a mineral systems approach 36 Tier-1 and Tier-2 targets as well as 3 large ‘carbonatite-type’ bodies
|Cleaning and mapping of historical Belgian open-pit mines
|The following historical Belgian mine pits were cleaned and mapped and all REE veins recorded: Rusutama, Bigugo and Gakara (ongoing)
|Kiyenzi in-fill drill core assay analysis
|An additional 1,306 Kiyenzi drill samples were assayed, made up of 1,174 infill core samples – sampling of gaps between original higher grade mineralisation intercepts – and 132 QAQC samples
|Exploration and bulk sampling of “large REE veins
|35 “large REE veins” (›10cm thick) exposed over various lateral and depth extents, at Gashirwe West and East, Gasenyi, Murambi North and Kiyenzi
|Trenching on Kiyenzi target
|2 trenches, for a combined length of 285m, excavated on top of the Klyenzi hill to determine if the REE mineralisation extend beyond the area that was drilled out in 2018
Using a combination of geophysical data and a comprehensive mapping database, accumulated over several years, TECT Geological Consulting have completed geological structural interpretation and surface exploration at Gakara, providing an updated JORC compliant Exploration Target for the project.
The presence of three large carbonatite bodies which represent the regional source of rare earth elements have been confirmed by this report, thereby underpinning the scale of Gakara’s mineralised system.
Located on the Western area of the mining licence along a NNE- trending structure, the southernmost carbonatite has a diameter of approximately 2.6 km.
The Exploration Target announced in October 2020 defines clear strategy for modular development at Gakara.
- The Initial Exploration Target covers nine high grade vein hosted areas of rare earth mineralisation containing 262,000 to 375,000 tonnes at a diluted grade of 7.0% to 12.0% total rare earth oxides (“TREO”), representing one of the world’s highest rare earth grades.
- The TECT study highlighted 36 Tier-1 and Tier-2 targets and 21 Tier 3 targets, increasing Rainbow’s original 32 targets.
- The Exploration Target is defined from only 10 of the 32 mineralised areas that have been identified by Rainbow to date – many other mineralised areas identified for future exploration can further expand the resource base.
- Further upside defined through breccia hosted mineralisation, with the Exploration Target containing 252,000 to 342,000 tonnes at 1.0% to 1.5% TREO, which could be developed as a parallel, lower grade processing stream.
JORC exploration target
See further details of the updated JORC exploration target.
Read the Maja Mining Ltd (Maja) Technical Report on Gakara.
Mining and Processing
Trial mining and processing, carried out by Rainbow since 2017, has demonstrated the deposit’s amenability to simple open pit mining and low-cost gravity separation from ore sourced from high-grade stockwork vein systems across the licence area.
Various mining methods were trialled as the team sought to evaluate the optimal mining method for a commercial-scale mine. The mineralised veins at Gakara have a high in-situ resource grade but are narrow and non-uniform in nature. Selective mechanical mining of ore delivers a grade of approximates 10% rare earth oxides, amongst the highest rare earth run of mine grades in the world, suitable for upgrade in our pilot processing plant.
Gakara has produced since its inception a high-value rare earth concentrate of 52-56% TREO, with low levels of radioactivity. Neodymium and praseodymium (NdPr), the critical input materials in permanent magnets, represent approximately 88% of the overall basket value (whilst being only 19.5% of the mass).
No reagents are used to produce Rainbow’s concentrate, delivering both a low environmental impact and a low processing cost, compared to more complex rare earth processing requirements.