The Vermiculite of the Day Book Dunite formation is type of Hydrophlogopite. Kulp,J.L and Brobst,D.A (1954) Notes on the dunite and the geochemistry of Vermiculite at the Day Book dunite deposit,Yancey County, North Carolina:Economic Geology,Vol.49 pp.211-220.The vermiculite from the Day Book dunite formation is a type of Hydrophlogopite. Kulp.J.L and Brobst,D.A (1954)Notes on the Dunite and the geochemistry of Vermiculite at the Day Book dunite deposit,Yancey County,North Carolina:Economic Geology,Vol.49,pp.211-220.