Vancouver – Disappointing drill results from a 658 metre drill program has prompted BHP Billiton (BHP-N) to stop working Caldera Resources’ (CDR-T) Tabletop diamond project in Western Australia.
Tabletop sits on an interpreted extension of crystalline basement rocks that extend from east Pilbara to the southeast into the country’s central region. Earlier work identified up to 40 high-priority magnetic targets considered prospective for marking kimberlites or lamprolites. Limited drilling on six targets in September 2000 was highlighted by a 19-metre interval of ultrabasic material probably composed of lamprolites and kimberlites.
Several other aeromagnetic targets are associated with heavy mineral anomalies, which include pyrope garnet/chrome spinel at one anomaly and microdiamond/chrome spinel at two other targets. The latest drill program tested 5 magnetic geophysical anomalies over the 20,800-sq.-km area but failed to yield favourable geochemical results.
The major was earning a 51% interest in the diamond prospects by spending A$1 million over five years.
With BHP now out of the picture, petrological work completed by Caldera on the drill samples have identified lapilli crystal lithic tuff from three of the targets. According to the junior, this fine-grained tuff material is indicative of potential crater lake sediments. The junior has also identified chrome spinels from five 1.5-kg samples collected from these targets. The spinels will be probed in order to determine whether they are of kimberlitic or lamproitic origin and six, 20-kg samples will be processed for microdiamonds.
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