I think so. Though, I think one of the Balmerans, the people who live on the Balmera, said it was more like a vibration through the rock. I mean, it's living rock, but it is still pretty much like rock.
[He nodded.]
They come in different sizes, and the Castle uses it for power because they give off a lot of energy. There's a whole process to extracting one, and it actually costs the Balmera energy to give one up. That's why the Alteans developed a rejuvenation process to replenish that energy. Taking too much of the crystal without replenishing the energy will eventually kill the Balmera.