It looks like flint (shape perhaps of little significance), but I can't find anything about flints in the area (and it doesn't seem likely from the general geology).
I can't see any definite characters that support the idea of it being a tooth; the overall shape can easily be misleading. So, to make an ID, closer inspection would be necessary, looking for cellular or biotic mineral structure, for instance.
Having examined again in light of your comments I agree that it is a lump of flint that must have found its way into my Zambia collecton by mistake. Sorry for confusion but thanks for link to Zambian geology..