A method and respect material for the production of chlorosilanes (primarily: trichlorosilane) and the deposition of high purity poly-silicon from these chlorosilanes. The source for the chlorosilane production consists of eutectic or hypo-eutectic copper- silicon, the concentration range of said copper-silicon is between 10 and 16 wt% silicon. The eutectic or hypo-eutectic copper-silicon is cast in a shape suitable for a chlorination reactor, where it is exposed to a process gas, which consists, at least partially, of HCI. The gas reacts at the surface of the eutectic or hypo-eutectic copper-silicon and extracts silicon in the form of volatile chlorosilane. The depleted eutectic or hypo- eutectic material might be afterwards recycled in such a way that the amount of extracted silicon is replenished and the material is re-cast into the material shape desired.