My company is involved with the engineering work for both this sector. Market capitalization really varies on each company's requirement, what I meant is that either they will setup an onshore processing facility or not. Mining mainly ships out their laterite and start building purification facilities once the they have accumulated signficant amount of low yield.
Stock wise....both are really volatile. If you know how read the charts right, you'll profit on both well (i.e. DIZ, NI,UNI,OV)