Central to the Blina Diamond Project is a diamondiferous palaeo-channel, discovered in 1995 and named Terrace 5 (Figure 1). This channel has been tracked over a distance of some 40km and drains the central section of the diamondiferous Ellendale lamproite field. Gravels from this system are characterised by containing significant concentrations of relatively large diamonds2. It is likely that there are multiple lamproitic sources for these diamonds that remain to be identified.
Figure 2: Terrace 5 Stratigraphy
Terrace 5 was once a major alluvial system with channel widths from 200-500m. Gravels (where present) are variable, but average about one metre in thickness. Diamonds recovered from the gravels are considered large, with an average stone size of around 0.42 carats. Most stones are of gem quality. The largest diamond recovered to date from Terrace 5 weighed 8.44 carats (from Pit 82)6, with stones larger than two carats common.1
2.1 Terrace 5 Bulk Sampling Program 2005
Any of the following which is italicised is taken from statutoryreports as referenced.