Toronto-listed Guyanor Ressources has discovered diamonds in a metamorphosed ultramafic rock within its Dachine permit area in French Guiana.
Guyanor, which is 70% owned by Golden Star Resources (TSE), has traced the rock, which it believes to be kimberlite, through 3.5 km of length and 0.5 km of width.
Guyanor and BHP Minerals agreed in December to explore jointly the Dachine permit area for the source of a secondary diamond occurrence identified in the 1970s. To date, six outcrops have been sampled, all of which have yielded microdiamonds. As well, samples from 11 shallow auger holes bored on the main ultramafic body have yielded microdiamonds, and recent results from a deeper hole (152 metres) revealed at least 2,658 microdiamonds in a 34.5-kg sample covering a length of 25 metres. A second, shallower hole, drilled on what is thought to be a younger, smaller ultramafic body, yielded little.
Results from three additional drill holes, which intersected the main body, are pending.
Processing of 1.8 tonnes of saprolite from auger holes yielded 8 macrodiamonds (greater than 1 mm), the largest being 2.4 mm in diameter. The recovered stones are off-white to grey or brown in color, and most contain inclusions. The microdiamonds recovered, by comparison, are dominantly brown in color, clear, and consist mainly of fragments, fragmented dodecahedrons and more complex crystal forms.
Four distinct populations of microdiamonds have been identified, the most important of which consists of clear, white microdiamonds; of these, the best stone found was a 0.6-mm, clear, white, perfect octahedron.
Based on these encouraging results, and contingent upon continued success, BHP (the operator) and Guyanor are contemplating a small bulk-sampling program, to be carried out in the second or third quarter.
Below are the results of sampling at the Dachine project:
Weathered bedrock samples
SampleWeightMicro-
(kg)diamonds
DR-018513
Outcrop B46.91
Outcrop C46.918
Outcrop D38.642
Outcrop E40.254
DACH-0476.323
Auger samples
DACT-01391036
DACT-0238645
DACT-0342.24
DACT-0440492
DACT-0544.240
DACT-0636.43
DACT-0734.7141
DACT-1118.4890
DACT-1218.613
DACT-1320.25
DACT-1418317
DACT-1521.10
Core samples, Hole DDAC-04
EE8.6 – 18.3 m12.50
E29.1 – 41.9 m2918
E79.6 – 105.1 m292
110.1 -137.8 m31.60
Core samples, Hole DDAC-05
10 – 26.4 m10.8169
E26.4 – 41.9 m20.96
E41.9 – 78.6 m48.7pending
E78.6 – 96.9 m22.3146
E96.9 – 126.8 m37.7486
126.8 -151.8 m34.52658
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