My grandmother was into crystal healing. She claimed they had healing powers, but I don't think there is scientific evidence on that, do you?
No I don't,I'm not into mysticism
I'm not sure it's mysticism. Its just a pseudoscientific alternative where people use crystals for medicine.
If it were,why is it not used the hospitals?
That is true, but I guess the stones have been used by cultures all over the world by many different people as healing objects. I guess if it's not harming anyone, its ok.
So when was the earliest time it was practiced?
Crystal healing dates back to at least 5000 years I think, even though it's heavily associated with the New Age Spiritual movement