The Quartz Mystery

I recently made this 16.5" necklace. I used snow quartz beads and this pendant that I received as a gift. I have no idea what kind of stone it is... I asked the question in the etsy.com forum and received SEVERAL different opinions on the matter. I think I'm leaning towards a quartz. What do you think?

I love the blue/green color of this pendant - It's one of my favorites!