Depending on usage, crystals should be cleansed and recharged every so often. For soft crystals (i.e., Angelite, Mangano Calcite, Turquoise, Malachite, Amber, etc.) and those crystals you use a lot, once a week is good for stones that you're using quite a bit. For crystals you use less, cleansing and recharging them once a month is probably good. There are other methods of doing this that are equally effective, but Selenite does them the fastest and easiest way, in my opinion. Salt has some excellent uses for cleansing and purifying, However, salt, wet or dry, is very rough on any rock or crystal and should never be used, in my opinion, to cleanse or recharge them. Some crystals like sunlight and some like moonlight for cleansing and recharging. If you have a number of crystals, carrying them outside can become a bit of a chore. You only need to set a crystal on Selenite for five minutes to cleanse and recharge the piece. You can leave anything sitting on Selenite as long as you wish, though. The rocks and crystals love the energy!