UserX
The best way to preserve cholesterol stones (floating stones) is to freeze them.
Some stones can be preserved in vinegar, and also formaldehide can be used.
Sometimes, if you wash stones in cold water, and then you expose them to the sun, they may dry and stay hard.
But, most cholesterol stones exposed to the air, get quickly attacked by aerobic bacteria, and get converted into sticky waxy liquid - bile acids.
Main ingrediaents of cholesterol stones are cholesterol, protein and pigment. Stones that are composed mainly of cholesterol are very soft and the best way to preserve them is by freezing. Stones that have more proteins (harder) and more calcium, can be preserved by drying on the sun.
Agnes