Cobaltoblödite

Cobaltoblödite is a rare cobalt mineral with the formula Na₂Co(SO₄)₂·4H₂O.^[2][3] Cobaltoblödite was found in the Blue Lizard mine, San Juan County, Utah, USA, which is known for secondary uranium minerals.^[4] Cobaltoblödite occurs intimately intergrown with manganese-, cobalt- and nickel-enriched blödite and a yet another new mineral - manganoblödite. Cobaltoblödite, as suggested by its name is a cobalt-analogue of blödite. It is also analogous to changoite, manganoblödite and nickelblödite - other members of the blödite group.^[3]

Cobaltoblödite
General
Category	Sulfate mineral
Formula	Na2Co(SO4)2·4H2O
IMA symbol	Cblö[1]
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/a
Unit cell	a = 11.15, b = 8.27, c = 5.54 [Å], β=100.52° (approximated); Z = 2
Identification
Color	Colorless (grains), reddish-pink (aggregates)
Crystal habit	Anhedral grains, in aggregates, forming crusts
Cleavage	None
Fracture	Uneven
Mohs scale hardness	2.5
Luster	Vitreous
Streak	White
Diaphaneity	Transparent
Specific gravity	2.29 (measured), 2.35 (calculated) (approximated)
Optical properties	Biaxal (-)
Refractive index	nα=1.50, nβ=1.50, nγ=1.51 (approximated)
References	[2][3]

Notes on chemistry

Manganoblödite is impure, containing admixtures of magnesium, manganese and nickel.^[2]

Association and origin

Besite blödite and cobaltoblödite, other minerals associated with manganoblödite include chalcanthite, gypsum, johannite, sideronatrite, a feldspar group-mineral and quartz.^[2]