Mineralpedia Details for Bayleyite

Named for Professor William Shirley Bayley, former American mineralogist and geologist at the University of Illinois who also worked for the United States Geological Survey.  Bayleyite is a rare mineral that can be found in localities in the United States, Canada, Morocco, Argentina, France, and Israel, among only a few others. It occurs as a coating or efflorescence along with other secondary uranium minerals and may be of post-mine origin, and is found typicality in sediment-hosted uranium deposits. Bayleyite is soluble in water and can rapidly dehydrate when exposed to air. It is quite radioactive and has a weak fluorescence of yellow-green to pastel green under both long-wave and short-wave ultraviolet light.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/bayleyite.pdf

Formula

Mg₂(UO₂)(CO₃)₃(H₂O)₁₂·6H₂O 

Crystal System

Monoclinic 

Cleavage

None, None, None 

Luster

Vitreous - Dull 

Color

yellow, pale yellow, yellowish white 

Streak

white 

Class

Monoclinic - Prismatic 

Fracture

Conchoidal 

Hardness

- 

WebMineral

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Mindat

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Light yellow acicular crystal sprays to 0.75mm.

Yellow, thin, lath-ilke crystals in groups and fans less than 1mm. I am undecided what the faint yellow material is. Perhaps just gypsum with inclusions.