Kozoite-(La), La(CO₃)(OH), a new mineral from Mitsukoshi, Hizen-cho, Saga Prefecture, Japan

Abstract

Kozoite-(La), (La, Nd, Ca)(CO₃)[(OH), (H₂O)], occurs in cavities of alkali olivine basalt at Mitsukoshi, Hizen-cho, Higashi Matsuura-gun, Saga Prefecture, Japan. Minute crystals of kozoite-(La) form a spherical aggregate with kozoite-(Nd). Concentric zoning textures of kozoite-(La) and kozoite-(Nd) can be observed on the fracture of the spherical aggregate. Kozoite-(La) is the La-analogue of kozoite-(Nd) and is a new member of ancylite group minerals. It is orthorhombic, Pmcn, a = 4.986(4) Å, b = 8.513(6) Å, c = 7.227(10) Å, V = 306.7(6) ų, Z = 4. The three strongest lines in the powder XRD patterns [d(Å), I/I₀, hkl] are (4.31, 100, 110 and 020); (3.69, 72, 111 and 021) and (2.93, 57, 121 and 102).