Now that the auroramine was shutdown, there is another site same as auroramine giving free 100GH/s for sign up. if you look at the site they offer.
10% ROI for a deposit of 0.002 to 0.49 BTC
12% ROI for a deposit of 0.5 to 0.99 BTC
15% ROI for a deposit of 1 BTC
Accept USD, BTC, ETH, DOGE, and LTC.
And get your investment back in Bitcoin!
Auto withdrawal to your BTC wallet every 24 hours
I think this is another scam, don't invest in this site.