I found this in Victorville, CA in a location known for finding black jade. It's a bluish color and a little translucent. I found some Amethyst on a hike a few weeks ago and that sparked a curiously in me and I'm wanting to learn.
Your rock most likely contains common opal or chalcedony (cryptocrystalline variety of quartz). You will be able to scratch opal with a sturdy steel knife blade but not chalcedony.