We know his father had the magnet release and black rings appear around his eyes when he activates this release. As we have seen from Gaara he has black rings around is eyes all the time and even when he was born.
As seen from the newest spoilers of chapter 674:
If translated correctly then Naruto has gained the magnet release through Shukaku's chakra. Shukaku must use the magnet release to control regular sand.
We already know Jinjuriki's gain the power of their Bijuu's as seen from Roshi who gained the lava release from Son goku. If we know that then Gaara must have a magnet release not just for gold sand like his father but regular sand as well which he should have gained from Shukaku.
In my opinion the magnet release combines the natures of Wind and Earth. All the metals used with the magnet release are minerals of earth like iron, metals used to make kunai, gold sand. The wind creates the ability to move these things freely. So regular sand is also a mineral of the earth so that should allow it to be manipulated using the magnet release.
Magnet release, magnets attract and repel which is what Gaara does with his sand.