What is this blue crystal? I was sorting out some old boxes in one of the rooms in my house, when I found a small container with about 10 grams of this blue crystalline powder. I assume that it contains some form of copper due to the colour, but the label's all ripped and I can't see the name of it.

So what compound is it?



It appears to glow in the image, but this is just the reflection from the camera flash and it doesn't look like this in real life.
As orthocresol also mentioned, it's probably copper sulfate. As you said, the blue color essentially gives it away.



(picture taken from Science Madness Wiki)