The Letlhakane mine consists of two kimberlite pipes and is one of a cluster of three kimberlite mines in central Botswana. Core logging and additional petrographic study classifies this deposit as a Group I, opaque-mineral and perovskite -rich altered probable monticellite kimberlite. Most of the kimberlite examined is massive volcaniclastic kimberlite, whilst rare layered volcaniclastic and magmatic kimberlite is also present.

Spinels are a ubiquitous component of kimberlites and their compositions are frequently used as petrogenetic indicators. The compositions of Letlhakane groundmass spinels will be used to fingerprint kimberlite facies by identifying the presence of several discrete batches of magma with unique evolution trends. The spinels are excellent indicators of these trends and are apparently immune to the affects of hydrothermal and subsequent alteration. Analysis has revealed that the Letlhakane spinel are unusually titanium-rich (TiO2 from 4.93 to 17.91 wt%), which correlates with other titanium-rich textural indicators such as the presence of prograde overgrowths of sphene around atolled-textured spinels and an unusually high proportion of perovskite to spinel of around 10:1, which is the inverse of a typical kimberlite.

Letlhakane and Damtshaa Mines, which are open-pit operations using traditional truck and shovel methods, and clustered in a radius of under 25km in the Central District of Botswana.

The Letlhakane mine has no processing facilities. Therefore, the diamond ore produced at Letlhakane is processed at a processing plant at its sister mine, Orapa diamond mine, about 50 km away.

The tonnes mined from A/K1 pit feed two processing plants, Orapa 1 and Orapa 2. The concept of diamond processing, entails stages of comminution to progressively reduce the particle size of the ore, and screen it into a feed size envelope desirable for the concentration process. A major outcome of the comminution process is diamond liberation; a process whereby the locked-up stones are released from the host rocks. Once the diamonds are liberated, they can now be separated from the gangue material into a concentrate by the Dense Medium Separation process.

Liberation is the fundamental activity of any diamond processing operation. The state of liberation in a plant, while not measurable, is diagnosed by the level of grind (fracture) completed by the plant at any given sub-stage of comminution. The total grind conducted by the plant is achieved by a combination of comminution equipment and recycle such that all material is reduced to below a desired size.

The combination of the comminution stages is also known as feed preparation. Subsequently, diamond concentration is achieved through a process known as dense medium separation (DMS). A concentrate is formed by utilizing the density differentials between the gangue or host rock and the diamonds. The final recovery stage is done by using x-ray machines in a separate plant, known as the ‘recovery plant’.