In general any one can keep pyramid in house. It will create the positive energy as a result because of its own geomatrical shape. The pyramid used to remove negativity of your place.
The placement of pyramid depends on the actual purpose. For ex.
Happy life - it should be placed. On North East corner.
House wifes feeling tired or some kind of disturbance while cooking - they can jeep the pyramid on the South west corner.
In sleeping room also you can place the pyramid.
Other area you can keep North west also
Vaasthu & cosmic divine energy consultant