Zellerite
Carbonate mineral
From Wikipedia, the free encyclopedia
Zellerite is a uranium mineral, named after its discoverer, geologist Howard Davis Zeller. It has a type locality of the Lucky MC uranium mine in Wyoming, USA. It was approved by the IMA in 1965, but was first published a year after its approval.[2]
| Zellerite | |
|---|---|
| |
| General | |
| Category | Minerals |
| Formula | Ca(UO2)(CO3)2 · 5H2O |
| IMA symbol | Zel[1] |
| Strunz classification | 5.EC.10 |
| Dana classification | 15.3.1.1 |
| Crystal system | Orthorhombic |
| Crystal class | H-M symbol: 2/m 2/m 2/m or mm2 |
| Space group | Pmmm or Pmn21 |
| Unit cell | 1,064.81 |
| Identification | |
| Color | White yellow, light lemon-yellow, lemon |
| Crystal habit | Acicular |
| Cleavage | One |
| Mohs scale hardness | 2 |
| Luster | Dull |
| Streak | White |
| Diaphaneity | Transparent, translucent |
| Specific gravity | 3.25 |
| Density | 3.25 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.536 nβ = 1.559 nγ = 1.697 |
| Birefringence | 0.161 |
| 2V angle | Measured: 30°- 45° Calculated: 48° |
| Dispersion | Weak r > v |
| Ultraviolet fluorescence | SW and LW Green patches |
| Other characteristics |  Radioactive |
Properties
Zellerite is a dimorph of meyrowitzite. It is a uranyl carbonate.[2] It is an acicular mineral, and occurs in crystals that resemble the shape of needles.[3] 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.[4] 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.,[2] 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%).[3] 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.[4]