Wish I could say that I found this pretty crystal cluster myself during a rockhounding jaunt, but alas, no. I did find the old battery operated Trail Blazer light at a flea market though. That's a little treasure to me.
Again, painting something as seemingly complicated as a crystal cluster is really all about observation and breaking down an object into shapes of color. In the end, it is most important to recreate the feeling, however, rather than being 100% literal which can wind up looking stiff.