Our chimes begin with lava, which flows from a volcano. Lava is molten rock. It can take many forms depending on the mix of elements in a given batch and the way and rate at which it cools. It is just a bit like baking cookies. Different ingredients make different flavors. How the cookies are baked will affect the texture; but with lava, it is the cooling rather than the baking that helps defines the nature of the end product. For instance, granite, basalt and obsidian all come from roughly the same kind of 'dough'. The difference is that granite is formed when lava, (or magma as it is called before it reaches the earths surface), is injected below the surface, and therefore cools very slowly due to the insulating effect of the surrounding rock. Under these conditions the various minerals will crystallize or 'freeze' at different temperatures. They will grow to a size that may easily be seen by the naked eye. What happens in the formation of basalt is not much different except that it is extruded upon the earths surface and cools much more quickly than granite; hence, the crystals have less time to grow and are much smaller, requiring a magnifying glass to see; obsidian, however, is quite different. Because it cools rapidly, there is no time for any crystals to form at all. Each molecule is like a separate entity floating within the rock. With no interlocking crystalline structure to reinforce itself, it becomes a glass. There is research that indicates that obsidian behaves like a very, very thick liquid. The important thing in terms of obsidian being perfect for chimes is that the absence of crystal boundaries means that sound waves can travel through the rock without interference, and its ringing properties are greatly enhanced.