CH-28 Mini-Bulk Sample Returns Grade of 0.27 Carats Per Tonne

October 25, 2011 PDF version
Peregrine Diamonds Ltd. (“Peregrine” or “the Company”) is pleased to report that a 32.54 tonne mini-bulk sample of surface material collected from the CH-28 kimberlite returned 8.94 carats of commercial-sized diamonds larger than the 0.85 mm sieve size, for a diamond grade of 0.27 carats per tonne (“cpt”).

The CH-28 kimberlite has an estimated surface expression of two hectares and is located on the 9,800 square kilometre Chidliak project (“Chidliak”), Baffin Island, Nunavut, Canada. CH-28 is approximately 50 kilometres north of the Southern Focus Area, an area at Chidliak with an eight kilometre radius that currently hosts six kimberlites with economic potential.

The mini-bulk sample from the CH-28 kimberlite was processed by dense media separation (“DMS”) at the Saskatchewan Research Council Geoanalytical Laboratories (“the SRC”). The diamond results are presented in square mesh sieve format in the following table.


Dry Sample Weight (tonnes) Numbers of Diamonds According to Sieve Size Fraction (mm) Total Diamonds Carats
(+0.85 mm)
Diamond Content (cpt) (+0.85 mm)
32.54 36 65 26 12 1 140 8.94 0.27

The diamond content of the CH-28 sample as determined by DMS processing may not be representative of the overall diamond content of the CH-28 kimberlite due to a number of factors including the limited surface area of the kimberlite from which the CH-28 sample was collected and the relatively small size of the sample.

The four largest diamonds were described by the SRC as a 0.98 carat brown tetrahexahedroid, a 0.44 carat white/colourless distorted crystal, a 0.37 carat off-white cubic diamond and a 0.37 carat white/colourless tetrahexahedroid. The remaining nine diamonds in the +2.36 mm sieve size range in weight from 0.15 to 0.35 carats, with one being white/colourless, another grey and the remaining seven off-white.

Images from CH-28 are available at the following link here.

The 32.54 tonne CH-28 sample was collected from in-situ surface material (subcrop) over an area measuring approximately 50 by 50 metres. The sample consisted of macrocrystic kimberlite with abundant indicator minerals. The sample collection and shipment process was conducted under strict chain of custody protocols and was supervised by senior Peregrine personnel.

At the SRC, the sample was crushed by a jaw crusher with a gap set at approximately 30 mm. The sample was then fed into a five tonne per hour DMS plant where it was subjected to scrubbing and two stages of crushing. DMS concentration was performed on +0.85-12.0 mm feed material. Heavy mineral concentrate from the DMS was treated through a two-stage Flow Sort x-ray sorter and vibrating grease table recovery circuit. The resulting concentrates were then hand-sorted for final diamond recovery using sealed glove boxes.

As an element of Peregrine’s Quality Assurance/Quality Control protocols, 179 numerically laser-etched natural diamond tracers ranging in size from 0.15 to 2.84 carats were added to the sample bags in the field and at the SRC, and 177, or 99 percent, of the tracers were recovered from the DMS concentrate.

The discovery of the CH-28 kimberlite was first reported on September 23, 2010. A 238.9 kilogram surface sample yielded 174 diamonds larger than the 0.106 mm sieve size, including five diamonds larger than the 0.850 mm sieve size which weigh a total of 0.196 carats. As reported on June 2, 2011, a core hole was drilled across CH-28 and a 393.1 kilogram sample of drill core yielded 251 diamonds larger than the 0.106 mm sieve size including 0.13 carats of commercial-size (+0.85 mm) stones.

The SRC is an independent laboratory that is accredited by the Standards Council of Canada to the ISO/IEC Guide 25 standard for diamond recovery by caustic fusion.

Mr. Peter Holmes, P.