Meisserite

Meisserite
General
Category	Sulfate mineral
Formula	Na5(UO2)(SO4)3(SO3OH)(H2O)
IMA symbol	Mss
Crystal system	Triclinic
Crystal class	Pinacoidal (1) (same H-M symbol)
Space group	P1
Unit cell	a = 5.32, b = 11.51, c = 13.56 [Å], α = 102.96°, β = 97.41°, γ = 91.46° (approximated); Z = 2
Identification
Color	Pale green to yellowish-green
Crystal habit	prismatic
Cleavage	{100} and {001}, fair
Tenacity	Very brittle
Mohs scale hardness	2
Luster	Vitreous
Streak	Very pale yellow
Diaphaneity	Translucent to transparent
Density	3.21 (calculated) (approximated)
Optical properties	Biaxal (-)
Refractive index	nα=1.51, nβ=1.55, nγ=1.56 (approximated)
Pleochroism	Colorless (X), pale yellow (Y), pale greenish-yellow (Z)
2V angle	60o
Dispersion	Weak
Other characteristics	Radioactive
References

Meisserite is a very rare uranium mineral with the formula Na₅(UO₂)(SO₄)₃(SO₃OH)(H₂O). It is interesting in being a natural uranyl salt with hydrosulfate (hydroxysulfate) anion, a feature shared with belakovskiite. Other chemically related minerals include fermiite, oppenheimerite, natrozippeite and plášilite. Most of these uranyl sulfate minerals was originally found in the Blue Lizard mine, San Juan County, Utah, USA. The mineral is named after Swiss mineralogist Nicolas Meisser.

Association and origin

Meisserite is associated with other sulfate minerals: belakovskiite, johannite, chalcanthite, copiapite, ferrinatrite, and gypsum. It is resulting from post-mining oxidation of the primary uranium mineral - uraninite.

Crystal structure

The crystal structure of meisserite is unique. The building elements include:

• pentagonal bipyramids of uranyl groups
• SO₄ groups

These elements link to form chains. Sodium cations are bonded to oxygen atoms in chains, to hydrosulfate groups and water.

References