Jericho kimberlite Pipe (History)

 

• The Jericho kimberlite is located 420 km northeast of Yellowknife in Nunavut
• 172 million years old kimberlite field
• Surface expression of Jericho pipe:      1.2 Hc

• 

  Three phases of kimberlite sampled (0.30 ct/tonne to 1.96 ct/tonne)
• Unusual number of large stones present
• 93 NQ & 57 PQ surface diamond drill holes and large underground bulk sample (9,401 tonnes)
• Feasibility study updated June 2003

Summary of Jericho large stones processed in bulk-sample:

• Largest diamond recovered is +40 carats, and the largest gem quality diamond is 23.89 carats.

Weight Class (carats)	# of Diamonds
+40 35 - 40 30 - 35 25 - 30 20 - 25 15 - 20 10 - 15 5 - 10	1 - 1 1 2 5 13 44

 

 

 

 

Underground Bulk Sample: 

• 257 m long decline driven to a depth of 75 m facilitated the extraction of a 14,550 tonne underground bulk sample from the Jericho pipe in 1996. Of this material, a 9,401 tonne representative sample was processed that yielded 10,539 carats of diamonds. A DTC (formerly CSO) appraisal returned US$59.61/carat for the complete parcel of diamonds.
• Re-valuation of diamonds in 2003 resulted in a modelled value of US$92 per carat for the Jericho diamonds.  

JD-3 kimberlite Pipe

• The JD-03 kimberlite is located 7 km west of the Jericho kimberlite pipe
• A 10.53 tonne mini-bulk sample collected from PQ diamond drilling yielded 7.34 carats (one stone 3.6 carat weight)
• Second 35.9 tonne test sample extracted from the JD-3 kimberlite pipe returned a total of 10.41 carats, for an overall sample grade of 0.29 carats per tonne
• A total of 13 diamonds weighing 0.1 carats or above were recovered from the 35.9 tonne test sample, and the two largest diamonds weighed 1.18 carats and 0.75 carats
• The 35.9 tonne test sample was extracted with small diameter reverse circulation drill (32.8 tonnes) and diamond PQ sized drill core (3.1 tonnes)
• A 1 mm square screen was used for the bottom cut-off size

Geological Resource (to a depth of 300 m):

Pipe	Pipe Area (ha)	Total Resource (million tonnes)	Grade (cts/t)
JD-3	1.8	10.5	0.35

•  

^{The potential quantity and grade of the JD-3 kimberlite is conceptual in nature, and there has been insufficient exploration to define a mineral resource, and it is uncertain if further exploration will result in the delineation of a mineral resource.}

2007 JD-3 Evaluation Drilling

• Collect a sample for refinement of grade and approximate value for the JD-3 diamonds
• Approximately 500 tonne sample collected in March 2007
• Utilized 17.5” reverse circulation (“RC”) drill
• 5 RC drill holes completed
• 1 HQ core diamond drill hole completed
• The JD-3 kimberlite bulk sample returned 3,746 diamonds larger than 0.85 millimetres, weighing 134.7 carats, resulting in an average grade of 0.27 carats per tonne.
• These diamonds were valued by the government diamond valuators at an average price of US$40 per carat.
• Based on the grade and value results of the 2007 bulk sample, no further exploration work is planned on the JD-3 kimberlite at this time.

 

Contwoyto-1 Pipe

The Contwoyto-1 kmberlite is a land-based pipe with dimensions of approximately 60m by 80m. The pipe lies on the eastern side of Contwoyto Lake,  just north of the long eastern bay. It was discovered in October 1997 after an obvious indicator and float train was found leading to a small depression that was coincident with a subtle break in the MAG signature of a diabase dyke.

Early caustic values from the discovery hole were quite encouraging. In the first 90.2kg of drill core, 143 diamonds larger than 0.1mm were recovered. In 1999, 15 delineation drill holes outlined the geometry of the pipe with good confidence. Further caustic on these holes showed high numbers of diamonds and encouraged further work.

In the summer of 1999, a 50 tonne mini-bulk sample was undertaken. Using a 6" core drill rig, nine vertical holes were drilled. A total of 50.1 tonnes of kimberlite was drilled and processed at Tahera's 1 Tph DMS plant located in North Vancouver. Based on preliminary geological interpretation, four phases were mapped during the program:

• Phase 1 (Upper Volcaniclastic Breccia) consisted of 11.801 tonnes (metric) from which 5.667 Ct were recovered for a grade of 0.48 Ct/tonne.
• Phase 2 (Hypabyssal) consisted of 3.054 tonnes (metric) from which 0.745 Ct were recovered for a grade of 0.244 Ct/tonne.
• Phase 3 (Lower Volcaniclastic Breccia) consisted of 10.972 tonnes (metric) from which 1.625 Ct were recovered for a grade of 0.148 Ct/tonne.
• Phase 4 (Olivine-Phyric bimodal) consisted of 24.28 tonnes (metric) from which 5.38 Ct were recovered for a grade of 0.222 Ct/tonne.

As part of the quality control program, the sorthouse tailings were re-crushed and reprocessed. As a result, an additional 0.181 Ct was extracted. In total, 50.1 tonnes of kimberlite was processed and 13.598 Ct were recovered (including the four phases and sorthouse tailings), for a grade of 0.271 Ct/tonne.

<sup>The potential quantity and grade of the Contwoyto kimberlite is conceptual in nature, and there has been insufficient exploration to define a Mineral Resource, and it is uncertain if further exploration will result in the delineation of a Mineral Resource for the Contwoyto kimberlite.

Footnote: The technical mineral disclosure in this document has been reviewed by Mr. Eugene Flood, a "qualified person" under National Instrument 43 -101, who is a consultant of Tahera Diamond Corporation.</sup>