Does anybody know much about iron mineralisation??Rio Tinto...

Does anybody know much about iron mineralisation??
Rio Tinto recently announced a 2.25 billion resource in Guniea,
"Both the Pic de Fon and Oueleba deposits are approximately 7.5 km in length and up to 1km wide. The two deposits are separated by approximately 4 km in a north south direction along the Simandou range."

The recent TTY report stated that iron minerlaisation extended for 20km to the north of Frances Creek and obviously the depth of the strike is vital but does anyone have any idea how much iron could be in a 20km strike?