The pumpellyite mineral series

Abstract

The bluish-green epidote-like mineral, pumpellyite, was first described by Palache and Vassar (1925) from the copper-bearing amygdaloidal lavas of the Lake Superior region. It has since been reported from many parts of the world in rocks which have undergone low grades of metamorphism, especially types such as amygdaloidal spilites and diabases (Burbank, 1927; Waldmann, 1934; Tsuboi, 1936; Quitzow, 1935, 1936; Klein, 1939; Laeroix, 1942; Seether, 1942; Zavaritsky, 1944:; Korzhinsky, ]944; de Roever, 1947a, b; Kvasha, 1950) and in glaueophane-schists and even eclogites in which pumpellyite is often associated with lawsonite (Irving, Vonsen, and Gonyer, 1932; Quitzow, 1935, 1936 ; Lacroix, 1942 ; Switzer, 1945 ; de Roever, 1947a, b, 1950). W. P. de Roever (1947a, 1950) has suggested a pumpellyitic facies of metamorphism as a lower-grade equivalent of his lawsoniteglaucophane subfacies, characterized by high confining pressure, but subordinate shearing stress and thermal influence, and passing into unmetamorphosed rocks.