I'm sorry, but again, you might want to hit the link I provided, the Brazilian mines are in fact open-pit, they don't even have to tunnel for the stuff, it's practically laying on the surface, and not in the jungle either, check the photos of the two largest and you'll see. In addition, these two mines in Brazil alone, are said to have so much proven easily accessible niobium, that they could supply world demand at current levels, for the next 500 years.