Germanium is a brittle, silvery-white, semi-metallic element and is one of the few substances that expands as it solidifies from the molten state. It has the same cubic crystal structure as diamond.
It has a high refractive index and is high transparency to infrared radiation. Germanium is a semiconductor and is one of the purest metals on earth (99.99999999999%). Vital Materials can refine up to 13N purity.