Ann: Diamond-Bearing Lamproite Discovered at Brooking, page-51

I found additional info...

Not the full length of 70m drill core was lab tested...

Of most interest was the lamproitic material identified in the HQ (63mm) diameter core from the one hole drilled at the Little Spring Creek prospect.

This lamproitic material was intersected close to surface and extended to a vertical depth of approximately 70 metres. Significantly, previous stream and surface sampling programs had produced highly-anomalous concentrations of diamonds and lamproite indicator minerals in the creek downstream of Little Spring Creek, indicating a possible proximal source (See ASX announcement 23 November 2017).

These recoveries included 24 diamonds, 3,906 chrome-spinels, nine pyropes and two picro-ilmenites1 . After initially undergoing petrographic analysis at Townend Mineral Laboratory to confirm if the core sample was lamproitic, intervals of core were selected for micro-diamond analysis from depths between 12.6m and 68.3m.

The initial sample treatment was performed by Diamond Recovery Services in Perth, where samples totalling 86.8kg were crushed and screened before undergoing heavy liquid separation and caustic fusion processing.

The coarse fraction (>0.4mm) was subjected to a milling process in place of the caustic fusion. The final concentrate was examined for micro-diamonds and macro-diamonds by Global Diamond Exploration Services Pty Ltd (“GDES”) down to a bottom screen size of 0.1mm.

A total of 119 diamonds - 112 micro-diamonds and 7 macro-diamonds (>0.5mm in at least 1 dimension) (Figure 1) - were recovered from the 86.8kg sample of core, thus confirming the lamproitic material extracted from Little Spring Creek as diamond-bearing. The largest macro-diamond recovered from this process was approximately 1.0mm x 0.6mm x 0.5mm in size.