Mad about sand !!?

[Dejan Pavlovic]

Hi everyone !
Our little boy eats chincilla dust daily ...Almost half of his poo is
consisted of sand (if you press it hard with your fingers - what you find is
just sand ).
Otherwise he eats , drinks and acts completely normal .
His cagemate doesn't eat chin. dust .
Is there something wrong ?
Should we remove it (dust) from their aquarium ?
Could it make any harm to him on long terms ?
Thanks !

Dejan & Nives
Maggie , Otto and Laureen