I have a crystal and I sort of maybe know how to use it

I don't often get thank you gifts as a legal assistant but when I do they tend to be interesting. Today I got this.

Suck it edible arrangements, I got a crystal! I think it's selenite? The client who gave it to me was telling me what it can be used for and not to wash it (um ok, no baths for my crystal) and when she finished I said "and you could also throw it at someone if you need to." I don't think she agreed with me but it's got some heft to it.

Right now the crystal is sitting on my desk at work. According to crystal sites selenite can be used to dispel negative energy. I'm going to give it a shot the next time a client is yelling at me over the phone.