Excellent - world class for species or very significant. (!!)
Confirmation
Validity:
Believed Valid
References
References:
[Von Bezing, K. L. et al. (1991) - The Kalahari manganese field : an update, Mineralogical Record, 22 (3), 279-302; Min Rec (2009) 40:78]; Mineralogical Record (2001) 32:252