| Paratooite-(La) | |
| Category: | Carbonate mineral |
| Formula: | (La,Sr,Ca)4CuCa(Na,Ca)2(CO3)8 |
| Imasymbol: | Pto-La[1] |
| Strunz: | 5/B.0; 5.AD.20 (Nickel-Strunz) |
| System: | Orthorhombic |
| Class: | Dipyramidal: mmm |
| Symmetry: | Pbam |
| Unit Cell: | a = 7.2250, b = 12.7626 c = 10.0559 [Å] |
| Color: | pale turquoise-blue to pale blue |
| Habit: | blades (sheaves) intergrown to form spray-like aggregates |
| Cleavage: | (possible) |
| Mohs: | 4 (probably) |
| Luster: | vitreous or pearly |
| Streak: | pale blue |
| Gravity: | 1.97-2.02 (measured) |
| Opticalprop: | 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: | 72.6 ° |
| References: | [2] [3] [4] |
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.[5] [6] [7] 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.[8] 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.[9]