I bought this rock in a shop and I don't know what kind of rock or mineral it is. It's a dark blue crystal and the bottom is a blue rock. If you touch the bottom of the rock your fingers will get a blue dust on them. At first i thought it was fluorite but it doesn't look similar
Going to the store and asking about the rock is going to be hard. The store is a small chain and there are many people that work at the store so I would have to bring the rock to store.
I tried to get close-up for you. These are what I got without my camera blurring out