Lanthanum

lanthanum

monazite

bastnasite-(La)

ancylite-(La)

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Formula: La
Lanthanide, rare earth element, not found in the native state
Specific gravity: 6.16
Hardness: 2.5 mohs
Colour: Silvery white
Melting point: 1540^oC
Boiling point: 2830^oC
Abundance in the Earth's crust: 34 parts per million by mass, 5 parts per million by moles (ChC).
Abundance in the Solar System: 2 parts per billion by mass, 0.01 parts per billion by moles (ChC).
Lanthanum usually exists as a trivalent ion, La³⁺, in its compounds; it is not found free in nature, but occurs mainly in the minerals monazite and bastnäsite-(La) (ChC).

Lanthanum-bearing minerals include:

Oxides - the oxide anion is O^2-
Fluorides - the fluoride anion is F^-
Carbonates - the carbonate anion is (CO₃)^2-
Phosphates - the phosphate anion is (P⁵⁺O₄)^3-
Arsenates - the arsenate anion is (As⁵⁺O₄)^3-
Nesosilicates - insular (Si⁴⁺O₄)^4- groups
Sorosilicates - (Si⁴⁺₂O₇)^6- groups
Cyclosilicates - (Si⁴⁺_nO_3n)^2n- groups
Phyllosilicates - (Si⁴⁺₂O₅)^2- groups

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