The Color adjustments to blue and black at bigger distance with the resistor, and these darker crystals are less pure. Nitrogen and aluminium are common impurities, and they influence the electrical conductivity of SiC.[19] The fabric fashioned inside the Acheson furnace may differ in purity, according to its length from https://www.quora.com/profile/Trevor-Flatcher-2/Exploring-the-High-Temperature-Performance-of-Silicon-Carbide-Special-Ceramics-https-www-macrocosmmaterial-com-news-E