I think that all asbestos occurs naturally. And that children play on an asbestos mountain in Canada, with no ill effects. But that South African asbestos is the main culprit in causing cancer, and that mainly in negative synergy with smoking.
It all has to do with the little fishhook like barbs that latch onto the lung walls deep down.
Talcum powder will do you in if you make a habit of inhaling it.
Somebody doesn't want this land developed or used.