Re: Stones being analyzed ???
Stones melt as the result of work of aerobic bacteria.
ONLY cholesterol stones melt (choleserol is from 60% to 99% of total composition ) ... not harder stones made from more protein and more calcium.
Stones get "infected" with bacteria while passing through bowel.
As soon as they are exposed to air, bacteria starts working differently then they could work inside liver/bowel.
Sometimes, it is possible to preserve stones by washing them in cold water and then exposing them to direct strong sunlight.
Sunlight kills bacteria, and stones get preserved, and slowly become dry and hard.
Other than that, preserving them in vinegar/alcohol/formaldefide may also be possible. (I have no experience)
Freezing stones is the best choice.
Agnes