re: Ann: Drilling update No. 9 - Agbaja Iron ... Near enough. With a lot more to come!
I play around with gold a fair bit, and S.G. tests are only done to find out the % of gold is, in the host rock. But, as with EIO, when you know what % the ore is, you don't have to worry about S.G.
Hope that helps. Probably, for the purpose of this exercise, 5 tonnes per cubic mtr. would be closer.