I've been doing a lot of research on the internet on taking care of crystals!
I came across two websites that give really good info on the care. Luckygemstones.com lists each stone and when you click it, and scroll down you will find the care guide. ie..sodalite is a hard stone, but water will erode the calcite in it so don't wash it. ametrine will change color if put with amethyst. stuff like that. also gives the MOH.
Ozark Rock Exchange was another extensive site, more on healing than care, but I still liked the luckygemstone one for the way they set it up.
Hh