Chinleite-(Nd), NaNd(SO₄)₂(H₂O), the Nd Analogue of Chinleite-(Y) from the Markey Mine, Red Canyon, San Juan County, Utah, USA

Abstract

Chinleite-(Nd) (IMA2022-051), NaNd(SO₄)₂(H₂O), is a new mineral discovered in efflorescence on tunnel walls in the Markey mine, Red Canyon, White Canyon district, San Juan County, Utah, USA. It occurs as colorless prisms with pyramidal terminations in association with gypsum and natrozippeite on asphaltite. Crystals are transparent with vitreous luster. The mineral has a white streak, Mohs hardness 2½–3, one good cleavage (probably on {100}), brittle tenacity, and a splintery fracture. The calculated density is 3.436 g/cm³. Electron probe microanalysis provided the empirical formula (Ca_0.538Na_0.395Nd_0.244Sm_0.150Ce_0.130Y_0.117Gd_0.113Dy_0.061Pr_0.043Sr_0.032Eu_0.039La_0.008Ho_0.006)_Σ1.876(SO₄)₂[(H₂O)_0.73(OH)_0.27]. Chinleite-(Nd) is trigonal, P3₂21, a = 6.9540(7), c = 12.8590(9) Å, V = 538.52(11) ų, and Z = 3. The structure of chinleite-(Nd) (R₁ = 0.0258 for 791 I > 2σI reflections), a three-dimensional framework consisting of SO₄ groups, irregular NaO₈ polyhedra, and NdO₉ distorted tri-capped trigonal prisms, is the same as that of chinleite-(Y) and similar to the structure of bassanite.

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