Paratooite-(La)

Paratooite-(La)
Paratooite-(La): Locality: Paratoo copper mine, Yunta, Olary Province, South Australia, Australia. Field of view 6 mm.
General
Category	Carbonate mineral
Formula (repeating unit)	(La,Sr,Ca)4CuCa(Na,Ca)2(CO3)8
IMA symbol	Pto-La
Strunz classification	5/B.0; 5.AD.20 (Nickel-Strunz)
Crystal system	Orthorhombic
Crystal class	Dipyramidal: mmm
Space group	Pbam
Unit cell	a = 7.2250, b = 12.7626 c = 10.0559 [Å]
Identification
Color	pale turquoise-blue to pale blue
Crystal habit	blades (sheaves) intergrown to form spray-like aggregates
Cleavage	{100} (possible)
Mohs scale hardness	4 (probably)
Luster	vitreous or pearly
Streak	pale blue
Specific gravity	1.97-2.02 (measured)
Optical properties	biaxial negative, α = 1.605(3), β = 1.696(3), γ = 1.752(2)
Pleochroism	moderate, very pale blue (X) to greenish blue (Y = Z)
2V angle	72.6 °
References

Paratooite-(La) is a complex lanthanum copper(II) calcium sodium carbonate mineral, representing a unique elemental combination among the known minerals. It is a secondary, weathering mineral. There is a heterovalent diadochy substitution of lanthanum by strontium and calcium; also sodium is substituted by calcium in the mineral. Its structure proved to be more difficult to describe within the initial approach. It was later shown to be a superstructure of another rare earth carbonate mineral, carbocernaite. The "-(La)" suffix in the mineral's name is known as Levinson suffix. It refers to the particular element, of a group of elements (notably lanthanides), that dominates in the particular structural site. As such, the element would show major, dominant occupancy at this particular site.