TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The iodine-containing salt is lithium iodide, sodium iodide, potassium iodide, rubidium iodide, strontium iodide, beryllium iodide, magnesium iodide, and/or calcium iodide. The non-useful dopant iodide is chosen from boron triiodide, aluminum triiodide, phosphorus triiodide, gallium triiodide, germanium(IV) iodide, indium triiodide and arsenic triiodide. The milled fluorspar ore comprises 72.2 wt.% calcium fluoride and remainder of silicon dioxide, or a non-stoichiometric ratio or other impurities for generating byproduct gypsum (16), other product materials with additives for improving salability and quality, and predetermined amount of glass obtained from consumers or industry for recycling. The impure byproduct silicon tetraiodide is reused as source for the distillation column. Preferred Process: A fluoride-containing byproduct is recycled by reacting fluoride-containing byproduct with iodine gas, to produce iodine-containing salt. A non-useful dopant iodide separated from the crude silicon tetraiodide gas, is discarded, sold, or aggregated for use in a separate, differently doped crystal. The removed dopant iodides are reintroduced into the pure silicon tetraiodide, to produce silicon alloys with physical or electrical properties reflecting the characteristics which are imparted by the additives. The distilled pure silicon tetraiodide material is primarily separated in a centrifuge, and processed to produce isotopically pure silicon and isotopically pure iodine. The collected iodine gas is cooled and sold. The collected iodine gas is recycled by reacting with a metallic ore, oxide, hydroxide, carbonate, or halide to produce iodine-containing salts. The impure silicon tetraiodide waste material collected from the distillation column is recycled through remainder of system, thermally decomposed, and the remaining liquid is quickly cooled to produce an impure silicon metal, and remaining iodine gas is recycled by reacting it with a metallic ore, oxide, hydroxide, carbonate, or halide to produce iodine-bearing salts. Preferred Components: The container is airtight, nonreactive to fluoride compound and heated at predetermined temperature to react the iodine-containing salt with the silicon tetrafluoride gas. The crystallization furnace enables Czochralski process, heat-exchanger method casting, directional solidification casting, edge-defined film growth, or string ribbon method to grow crystalline material directly from a melt. The cold trap is maintained at less than 200 degrees C for condensation of silicon tetrafluoride. The other intermediate compounds are not condensed when cold trap is maintained at less than 200 degrees C. The container is designed such that the iodine-containing salt is heated and held in a nonreactive container within the large container, such as a nickel crucible, to minimize risk of high-temperature reaction within the large container.