- formally a semiconductor, acts like a metal especially in liquid form - second most common element in Earth's crust (as SiO₂) ## Types ### Metallurgical grade (MG-Si) - Si content ~99% - produced in submerged arc furnace #### Uses - alloying of aluminum --> 41% - silicones --> 355 - solar-grade Si production --> 12% - electronics --> 3% - 5x increase over past 20 years (mostly China) - energy mix over 50% renewable ### Ferrosilicon (FeSi) - mixture of iron and silicon (50-95% Si) - similar process to MG-Si production - focus of Icelandic smelters #### Uses - Carbon, stainless steel production