Formula: KMg3(AlSi3O10)(OH)2 Monoclinic
Phlogopite is a tan mica found most often in magnesium-rich rocks such as marbles, calc-silicate and ultramafic rocks.
KENOSHA COUNTY: Phlogopite occurs in a subsurface, diamond-bearing lamprophyre diatreme, discovered within the outskirts of Kenosha (Carlson and Adams, 1997).
ONEIDA COUNTY: Phlogopite occurs in some of the sulfide-rich metamorphosed carbonate rocks in the Lynne massive sulfide deposit. Associated minerals are talc, chlorite, pyrite, pyrrhotite and galena (Adams, 1996).