Well considering Xstrata only has 4 or 5 nickel mines that really isnt saying much I believe Raglan would be the highest grade Xstrata nickel mine.

At the end of 2005, Falconbridge estimated that Raglan had proven and probable reserves of 14.85Mt grading 2.8% nickel and 0.77% copper. Measured and indicated resources totalled a further 3.4Mt at 2.2% nickel and 0.8% copper, with inferred resources of 7.7Mt at 3.0% nickel and 0.8% copper. Exploration during 2005 outlined 2.5Mt of new resources.

That being said expecting 5% Ni over more 10m is a little ridiculous.