According to Vastu Shastra, black marble should be placed on the floor in the north direction. If you get black colored marble installed in some part of this direction, then you will get a lot of benefits. Due to this, no one in the family has any kind of fear. Everyone fearlessly does his work and gets success in it.
The middle son of the house gets the most benefit of the black colored floor in the north direction and our ears get the most benefit from it in the body. This strengthens our hearing.