How long does it take for a skeleton to turn to dust?

Question

In a sealed stone coffin in a sealed stone crypt, how long would it take for a skeleton to turn to dust?

Answer 1

It depends. In normal conditions, perhaps a body buried in soil, it will take 20 years for the acids in the soil to break down the skeleton.

If the body was sealed extremely well, with no traces of soil or acids, no chemical agents, etc. the skeleton may well survive up to thousands of years. That's how we come across mummies that are still intact, bone, skin and cloth.