For some time research workers have directed their attention to the study of ferriferous minerals. Researches on iron ores have led us to take up this problem. We shall give here the results of our observations on some minerals considered to be pure, belonging to the collection of the Museum National d'Histoire Naturelle, and on samples extracted by sedimentation from various ores.
This shows that the different samples belong to three types, with 10Å, 14Å and 7Å spacing. We will consider only the last two.
1. 14Å type (chlorite).—This includes the Chamoson chamosite, the bavalite from Bas-Vallon, metachlorite from Radauthal, and the chlorites extracted from ores from Soumont (Calvados), Auboue, Angevilliers, Andun-le-Tiche, Godbrańge (Lorraine).