Can't say that I've had any experience, good or bad, with moonstone. I have always felt drawn to it though. Since it's so plentiful where I live, my mother and I work a lot with quartz (both rose and regular) and obsidian. My mother used to have a large quartz crystal ball that she used for scrying (unfortunately her stepbrother stole it). She told me that obsidian is also good to use for scrying. We also like to use obsidian needles for other rituals and crafts. They make really nice chimes and the larger needles makes nice athames if you know how to shape them.