This group is the same as the regular arsenate ion group except that one of the four oxygens is replaced by an hydroxide or OH group. O. Other arsenates with this chemical oddity include pharmacolite , guerinite and picropharmacolite , all of which are associated with sainfeldite. The mineral hureaulite is similar, but with a phosphate as the affected ion group. Color is mostly a pale pink, white or colorless. Luster is vitreous.
Crystals are transparent to translucent.
Cleavage is absent. Streak is white. Associated Minerals are pharmacolite , guerinite , picropharmacolite and other secondary arsenates. Notable Occurrences include Richelsdorf, Germany and Ste. Best Field Indicators are color, locality, associations and crystal habit.