Zellerite is a
dimorph of
meyrowitzite. It is a uranyl carbonate. It can occur as fine hairlike fibers as well. The size of each crystal is up to 2 mm, and it grows in roughly radial aggregates, veinlets, and incrustations. Elongation is possible. It has
pleochroic attributes, which is an optical phenomenon. Depending on which axis the specimen is being inspected, it can occur as it changes color. Upon being inspected on the x or y axis, the mineral can seem to be colorless, but on the z axis, it is seen in a pale yellow color. The mineral also shows
luminescence. Under both a short wave and a long wave
ultraviolet light, it
fluoresces in green patches., which is typical for
Uranium compounds. The fully hydrated form of the mineral is lemon yellow, but in transmitted light, it has a very pale yellow color. The dehydrated version of the mineral is called
metazellerite. Zellerite is also radioactive: the concentration of the mineral per
Gamma Ray American Petroleum Institute Units is 280.20, due to it consisting of 45.76% uranium. The remaining constituents are oxygen (39.98%), calcium (7.70%), carbon (4.62%) and hydrogen (1.94%). This rare mineral forms in the weathering zone as an oxidation product of uraninite-coffinite, in the presence of an oxidizing pyrite, where the pH is greater than 7 and the
partial pressure of carbon dioxide is greater than the atmosphere's. It is associated with metazellerite,
gypsum,
uranophane,
meta-autunite,
schoepite, iron sulfides,
limonite and
opal. ==References==