It is typically green and forms small acicular crystals. Specimens from the classic mines of Cornwall, England are often associated with other rare minerals such as pharmacosiderite and beudantite , and these specimens are much sought after. Arthurite is unusual in that it contains a variety of anions, namely arsenate, phosphate and sulfate. Arthurite lends its name to a small group of rather obscure minerals called the Arthurite Group . The A in the formula can be either arsenic or phosphorous.
Color is apple green to emerald green.
Luster is vitreous to pearly. Crystals are translucent. Crystal System is monoclinic. Crystal Habits include prismatic to acicular crystals and globular aggregates and crusts. Cleavage is not observed.