The two minerals are in a series in which the arsenate ion group in arsentsumebite is replaced by a phosphate ion group in tsumebite. The two differ only slightly mostly because the structure is the same in the two minerals. Both are formed in the oxidation zone of lead-copper ore deposits. Both minerals are unusual in that they have two ion groups instead of the usual one in most minerals. It the case of tsumebite, it has a phosphate ion group and a sulfate ion group.
Color is emerald green and yellow-green.
Luster is vitreous. Transparency crystals are transparent to translucent. Crystal System is monoclinic. Crystal Habits include tabular crystals that can form twinned trillings and also as crusts and spherules. Streak is green.