Known as Amdzhaoa among Garruw, this crystal is the general term for any kind of crystal that is exposed to the energy in the storms of Thaiterra. Once exposed, usually via a lightning strike, the crystals take on specific properties that allow them to be used as batteries. Sort of. In theory. No one's actually been able to harness the energy. But it's there, and the transformation that the crystals undergo renders them very beautiful and unique, and moreover the energy is incredibly stable. Among the scientists of the Garruw (and there are a lot of those), doing amdzhaoa research is a sign of immense responsibility. It is seen as the key to their dreams of spaceflight. There are legends of those who might have once harnessed the power of the crystals, but these are seen as fanciful myth. (See The Loss of the Travorgan) In theory, one largish crystal could power the entire Dome for a Thaiterran year. In practice, people use it in flashlights because it's nigh impossible to extract any more energy from the stones than that.
Amdzha crystals tend to look a lot like the base crystals they were transformed from, so you get all different types and colors. After transformation, though, there is a slight glow.
Physical & Chemical Properties
When it's new, it's pretty hot and should not be touched, even by the heat-resistant garruw. It will maintain a slightly warmer temperature and tends to draw up heat and retain from the sun more easily than other stones, and so can be identified by temperature, and by how well it absorbs the energy around it.
History & Usage
The garruw realized the power of the amdzhaoa early on in history. They knew they consumed the energy of the storms, and nothing else did, and it was a source of their early superiority. Then they observed that there were types of crystals that would also absorb the energy, taking full lightning strikes and not being destroyed. As such, they realized that the crystals were full of energy, and early science informed them that these massive troves of power would need to be harnessed if they would ever make it to the stars.
Humans can use the crystals as batteries, to a limited degree. It's more for interest and a unique experience than anything, because the crystals tend to keep their energy, and finding ways to extract it has been difficult. The batteries and power sources that have been modified to use them don't tend to be all that efficient.
Cultural Significance and Usage
Amdzhaoa has a great deal of significance for the Garruw, because it represents the promise of power. They collect it avidly, even though it's quite common, and projects that involve experimenting on the crystals usually get a large portion of funding. In the past, having a significant store of amdzhaoa has been a source of political power.