aprilia7

I'm looking for a bit of guidance with this problem if anyone could help please. I have a 'leaky' capacitor 100pF parallel plate with a 'mica' dialectric of relative permittivity Er=12 and resistivity p=10 to the power 14 ohm/m. Ineed to calc the leakage resistance? I know the Er value for mica is 7 so the value of 12 is probably due to it being 'leaky' but i am just unsure of my next step. any help would be greatly appreciated thanks Paul