A crystal to ward off negativity?

Lately I've been getting lots of negative energy at work. Maybe I should bring in a few crystals and put them in a glass vase on my desk.

I have a clear glass vase at home that I've filled with all kinds of different crystals. I would just go to a local store that sold them and hold them in my hand and if I liked the way the stone felt, then I would buy it.

I don't know how much of what I feel for crystals comes for my love of rocks (I love wood too, basically anything that is nature) or just how the stone feels physically, or another connection. I do know that one time I was at this store, I felt a stone that literally made me feel sick to my stomache when I touched it. It felt clammy in my hand and I immediately dropped it back into it's place on the shelf. The lady that worked there asked me about it and I told her I just didn't like how it felt. I was in the store later and saw that those stones were in a locked display case. I wondered why, but didn't ask. I wish I could remember the name of the stone. It was pinkish white and more round/oblong shape. It had veins of a slate blue color running through it. My hands feel sweaty now just thinking about it. Weird.

Nuummite. Exceptionally protective,,,apparently.