Named for the 19th. century Italian mining engineer, Quintino Sella, this rare magnesium fluoride reaches its zenith at Brumado - but specimens are very rare and good ones from just a few pockets. This is a large, complex crystal which exhibits incredible clarity and glassy luster. BETTER In PERSON! It is shockingly and totally colorless - not even a trace of hue. Also a floater. Zinn purchased this in 1992.