Paramarkeyite, a new calcium-uranyl-carbonate mineral from the Markey mine, San Juan County, Utah, USA
| Authors | |
|---|---|
| Year of publication | 2022 |
| Type | Article in Periodical |
| Magazine / Source | Mineralogical Magazine |
| MU Faculty or unit | |
| Citation | |
| Web | https://pubs.geoscienceworld.org/minmag/article-abstract/86/1/27/612393/Paramarkeyite-a-new-calcium-uranyl-carbonate |
| Doi | http://dx.doi.org/10.1180/mgm.2021.100 |
| Keywords | paramarkeyite; new mineral; uranyl tricarbonate; crystal structure; markeyite; natromarkeyite; pseudomarkeyite; Markey mine; Utah; USA |
| Description | The new mineral paramarkeyite (IMA2021-024), Ca-2(UO2)(CO3)(3).5H(2)O, was found in the Markey mine, San Juan County, Utah, USA, where it occurs as a secondary phase on gypsum-coated asphaltum in association with andersonite, calcite, gypsum and natromarkeyite. Paramarkeyite crystals are transparent, pale green-yellow, striated tablets, up to 0.11 mm across. The mineral has white streak and vitreous lustre. It exhibits moderate bluish-white fluorescence (405 nm laser). It is very brittle with irregular, curved fracture and a Mohs hardness of 21/2. It has an excellent {100} cleavage and probably two good cleavages on {010} and {001}. The measured density is 2.91(2) g cm(-3). Optically, the mineral is biaxial (-) with alpha = 1.550(2), beta = 1.556(2), gamma = 1.558(2) (white light); 2V = 60(2)degrees; strong r > v dispersion; orientation: Y = b; nonpleochroic. The Raman spectrum exhibits bands consistent with UO22+, CO32- and O-H. Electron microprobe analysis provided the empirical formula (Ca1.83Na0.20Sr0.03)(sigma 2.05)(UO2)(CO3)(3).5H(2)O (+0.07 H). Paramarkeyite is monoclinic, P2(1)/n, a = 17.9507(7), b = 18.1030(8), c = 18.3688(13) angstrom, beta = 108.029(8)degrees, V = 5676.1(6) angstrom(3) and Z = 16. The structure of paramarkeyite (R-1 = 0.0647 for 6657 I > 2 sigma I) contains uranyl tricarbonate clusters that are linked by Ca-O polyhedra to form heteropolyhedral layers. The structure of paramarkeyite is very similar to those of markeyite, natromarkeyite and pseudomarkeyite. |
| Related projects: |