Magnum’s 74% owned Gravelotte Project is located in the Limpopo province of South Africa. Emeralds were discovered in the province in 1927 and since then several companies have explored for and mined within the broader region for emeralds.
From 1929 to 1982 the total recorded emerald production from the Gravelotte Project as well as the area surrounding the nearby Gravelotte township was nearly 113 million carats.
It is reported that during the 1960’s the Gravelotte Project itself was the largest mine of its type in the world, employing over 400 sorters.
The host rocks at Gravelotte are 3.3 billion year old Archaean greenstone schists enclosed and intruded by younger Archaean granitic rock and late stage albite-quartz pegmatoids. The emerald mineralisation is closely related to the pegmatoids.
The emerald-bearing zones and their sub-divisions are as follows:
Gravelotte Location Plan
Since acquiring the project, Magnum has collated the historical data base and used this as a basis to better understand the geology, structure and controls of mineralisation within the project area.
As a forerunner to potential commercial production the Company has also maintained and refurbished much of the extensive mine site infrastructure at Gravelotte which includes offices, laboratory, workshops, garages, management accommodation complex and a mine hostel to accommodate mine workers.
The Gravelotte mine site is well situated with utilities and logistics being serviced by ESKOM grid power, has a sealed road to the mine gate and has a working airstrip.
The historic data base and existing open pits provide the Company with a ready data base to fast track evaluation of the project. Critical information that was still required was an understanding of the mining and milling characteristics of the Gravelotte rocks - particularly to ensure the least possible damage to the emeralds during these activities.
During the past year the Company consequently completed the first part of this evaluation by undertaking the trial mining, milling and processing of the extensive waste and low grade rock dumps available at Gravelotte. Following the successful completion of this exercise the Company has geared up for stage 2 of this programme - which is to extend the trial mining, milling and processing to hard rock to be mined from the existing open pits on site.
Trial Mining Phase 2
The Trial Mining Phase 2 involves the mining and processing of around 8,000 tonnes of hard rock from multiple locations within the existing Cobra North and Discovery pits.
Contemporaneous with the mining of the hard rock Magnum will commission a crushing and washing plant capable of processing around 2,000 tonnes per month.
The resultant crushed and washed material will then be processed through an XRF sorter with the emeralds produced batched and then provided during the second half of calendar 2019 for sale to various buyers to ascertain the price range for the Gravelotte stones.
An independent mining contractor has been engaged and mining commenced in late-March and estimated to take around 25-30 days for completion (weather permitting).
The crushing and washing plant arrived on-site in mid-March and commissioning was completed by the end of the month.
Recovery of emeralds utilising XRF technology is scheduled to commence in May.
In preparation for the Phase 2 trial mining operation, upgrades and refurbishments were undertaken to the electrical and water infrastructure onsite.
In addition, the upgrading of 1.2km section of the perimeter fencing, which was not previously electrified, was completed in January and completes the electrification of the entire perimeter fence for the first time. Further security upgrades to the site access road will commence once the perimeter upgrade is completed.
What is the rationale for the Trial Mining Phase 2 Operation?
The Trial Mining Phase 2 has been designed to recover a parcel of emeralds from Gravelotte of a sufficient size to allow a commercial assessment of pricing for the emeralds through a sale process.
There has been significant increase in demand for emeralds reported since 2000 so this will provide vital data for assessing the current demand and consequent pricing for emerald product from Gravelotte.
The Trial Mining Phase 2 will also provide geological, mining, processing and recovery data for input into financial modelling for a potential future commercial mining operation.
This data, together with extensive existing drill data and information from a proposed small drill programme later this year, will allow Magnum to prepare a JORC compliant resource statement for the Cobra North, Cobra South and Discovery pits.