Thanks for your considered comments.Please name major shallow...

Thanks for your considered comments.

Please name major shallow nickel sulphide deposits?

Nickel occurs in essentially two ore types; magmatic sulphides and ('wet' or 'dry') laterites.

The sulphides typically are found hundreds of metres below ground with principle mineralisation including pentlandite (Ni, Fe)9S8 .

Major deposits such as those in Canada and Russia have historically provided the bulk of nickel production. Nickel laterites on the other hand are found nearer or at the surface and are generally classified as limonitic (the upper layer, based on nickeliferous limonite; (Fe, Ni)O(OH)) or saprolitic (the lower layer, based on hydrous nickel silicate; (Ni, Mg)3Si2O5O5(OH)).

Re acid leachability: Method ME-MS41W is a 1:1 ratio of nitric and hydrochloric acids, both powerful acids. There is nothing weak about it. The reference to 'weak' is entirely relative ie compared with Method ME-MS41L™ a mixture of nitric and hydrochloric acids in a 1:3 ratio. Both are used for trace detection. They identify the particular rare each elements in the lab. These days their use in actual mining and processing is limited due to the high level of toxic waste they produce and the environmental damage. Imagine how green groups and indigenous owners would react to powerful acids being used to leach RREs?
My opinions are based on my research and industry experience.