Fermiite Explained

Fermiite
Category:	Sulfate mineral
Formula:	Na4(UO2)(SO4)3·3H2O
Imasymbol:	Fmi^[1]
System:	Orthorhombic
Class:	Pyramidal (mm2) H-M symbol: (mm2)
Symmetry:	Pmn21
Unit Cell:	a = 11.84, b = 7.87 c = 15.33 [Å] (approximated); Z = 4
Color:	Pale greenish-yellow
Habit:	prismatic
Cleavage:	None
Tenacity:	Brittle
Mohs:	2.5
Streak:	White
Diaphaneity:	Transparent
Density:	3.31 (calculated); 3.23 (measured)
Opticalprop:	Biaxal (+)
Refractive:	nα=1.52, nβ=1.53, nγ=1.57 (approximated)
Pleochroism:	Colourless (X & Y), pale greenish-yellow (Z)
2V:	50^o (calculated)
Other:	Radioactive
References:	^[2]

Fermiite is a rare uranium mineral with the formula Na₄(UO₂)(SO₄)₃·3H₂O.^[3] Chemically related minerals include oppenheimerite, meisserite (which is also structurally-related to fermiite), belakovskiite, natrozippeite and plášilite.^{[4] [5] [6] [7] [8]} Fermiite comes from the Blue Lizard mine, San Juan County, Utah, USA, which is known for many rare uranium minerals.^{[9] [10] [11]} The name honors Enrico Fermi (1901–1954).^[10]

Association

Fermiite is closely associated with numerous other sulfate minerals: oppenheimerite, bluelizardite, wetherillite, blödite, manganoblödite, chalcanthite, epsomite, gypsum, hexahydrite, kröhnkite, sideronatrite and tamarugite.

Crystal structure

The main building block of the crystal structure of fermiite is a chain of the composition (UO₂)(SO₄)₃. Chains are connected with five types of Na-O polyhedra.

References

1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
2. Kampf, A.R., Plášil, J., Kasatkin, A.V., Marty, J., and Čejka, J., 2015. Fermiite, Na4(UO2)(SO4)3·3H2O and oppenheimerite, Na2(UO2)(SO4)2·3H2O, two new uranyl sulfate minerals from the Blue Lizard mine, San Juan County, Utah, USA. Mineralogical Magazine 79(5), 1123-1142
3. Kampf, A.R., Plášil, J., Kasatkin, A.V., Marty, J., and Čejka, J., 2015. Fermiite, Na₄(UO₂)(SO₄)₃·3H₂O and oppenheimerite, Na₂(UO₂)(SO₄)₂·3H₂O, two new uranyl sulfate minerals from the Blue Lizard mine, San Juan County, Utah, USA. Mineralogical Magazine 79(5), 1123-1142
4. Web site: Oppenheimerite: Oppenheimerite mineral information and data . Mindat.org . 2016-03-10.
5. Web site: Meisserite: Meisserite mineral information and data . Mindat.org . 2016-03-10.
6. Web site: Belakovskiite: Belakovskiite mineral information and data . Mindat.org . 2016-03-10.
7. Web site: Natrozippeite: Natrozippeite mineral information and data . Mindat.org . 2016-03-10.
8. Web site: Plášilite: Plášilite mineral information and data . Mindat.org . 2016-03-10.
9. Kampf, A.R., Plášil, J., Kasatkin, A.V., Marty, J., and Čejka, J., 2015. Fermiite, Na4(UO2)(SO4)3·3H2O and oppenheimerite, Na2(UO2)(SO4)2·3H2O, two new uranyl sulfate minerals from the Blue Lizard mine, San Juan County, Utah, USA. Mineralogical Magazine 79(5), 1123-1142
10. Web site: Fermiite: Fermiite mineral information and data . Mindat.org . 2016-03-04.
11. Web site: Blue Lizard Mine, Chocolate Drop, Red Canyon, White Canyon District, San Juan Co., Utah, USA - Mindat.org . Mindat.org . 2016-03-04.