In Vastu Shastra today, Acharya Indu Prakash talks about putting mirrors in the south direction. Many people recommend putting mirrors in the south direction for business growth, but according to Vastu Shastra this is not considered auspicious.
The north direction is considered to be the direction of Kubera, the god of wealth, and by putting a mirror in the south direction, the image coming from the north will appear in the mirror, which is not right. Since the lord of the south direction is Yama, installing mirrors in this direction will not benefit Kubera i.e. will not benefit in wealth. Along with this, in the house, a mirror should never be placed which is very heavy, spiked or whose edge is broken. Also, a glass with three corners should not be put, this increases negativity.