waylandite

Waylandite is the phosphate analogue of arsenowaylandite and the aluminum analogue of zaïrite. The mineral was approved by the IMA in 1962, and was published the same year. Waylandite was named in honor of Edgar James Wayland. It is a member of the alunite supergroup, and a member of the plumbogummite – also known as crandallite – group. So far, only two bismuth-bearing members of the alunite supergroup are known, one of which is waylandite, alongside its ferric iron analogue zaïrite.

== Properties == Waylandite forms tiny crystals up to 0.5 mm, but it can also occur as compact fine-grained powder. It can form pseudocubic and pseudohexagonal crystals. It mainly consists of oxygen (38.49%) and bismuth (35.91%), but otherwise contains aluminum (13.91%), phosphorus (10.65%), and a small amount of hydrogen (1.04%). Waylandite does not display any radioactive properties. In its formula, bismuth may be replaced by calcium, and phosphorus may be replaced by silicon. It is often twinned in a cyclic manner, meaning three or more individual crystals are twinned according to the same law but without the twinning planes or axes being parallel. Most minerals of the alunite group have rhombohedral symmetry, of which waylandite is no exception. The arsenate analogue of waylandite supposedly exists, however its description was incomplete. Scharm described it in 1994, and named it arsenowaylandite, however did not submit either the name or the mineral to the International Mineralogical Association.