Mawbyite is a lead iron zinc arsenate that was named in honor of Maurice Alan Edgar Mawby.

[3] The relationship between helmutwinklerite – which shares a similar formula with tsumcorite's – and mawbyite had been suggested, but due to lack of data it remains unclear.

Mawbyite has a number of habits, the most prevalent one being a "dogtooth"-like bladed crystals, which can reach up to 0.15 mm in length, and the dominant forms include {110}, {101} and with minor {001}.

[2] Mawbyite has a conchoidal fracture, where breaking it results in smooth and curvy surfaces resembling a seashell.

[4] The pure ferric end-member of the mineral is dimorphous with carminite, meaning they share the same formula but form different crystal structures.

It mainly consists of lead (35.12%), oxygen (24.16%), arsenic (23.09%) and iron (16.35%) by weight, but otherwise has zinc (1.01%) and contains a negligible amount of hydrogen (0.28%) as well.

At Moldava in the Czech Republic, it can be found in the oxidization zone of silver-lead-copper-bismuth mineralization in fluorite, barite, and quartz veins.

At the former location, mawbyite is associated with duftite, bayldonite, hidalgoite, pharmacosiderite, segnitite, corkite-beudantite, adamite-olivenite, and other iron-manganese oxides.