The answer
The Natroun Valley is known to have nitric acid, but that is not the reason for the preservation of the bodies of some of the saints. When a saint's body is preserved, it is truly a miracle, and not the reason of the use of any kind of preservative or embalming practices. The reposed are laid to rest in crypts and not directly in the ground. There are not many cases in which it is known that the body of a particular pious person who reposed did not decay. If it was generalized, perhaps one could reach the conclusion that it is because of elements used in the burials.Answered by His Eminence Metropolitan Youssef (opens in a new tab)