Obsidian rock forms from molten lava that cooled very quickly and had no time to form into glass. It is said to be a type of volcanic glass, and is found in a number of places worldwide. There are a number of different variations of this mineral, and it comes in a range of types and colors.
I've been here a number of times, however I purchased a few gemstone rings the last time. They are beautiful. The atmosphere is a natural vibe. This is a place you NEED to seek out.