Lukechangite-(Ce), a new rare-earth-fluorocarbonate mineral from Mont Saint-Hilaire, Quebec

Abstract

Other| December 01, 1997 Lukechangite-(Ce), a new rare-earth-fluorocarbonate mineral from Mont Saint-Hilaire, Quebec Joel D. Grice; Joel D. Grice Canadian Museum of Nature, Research Division, Ottawa, ON, Canada Search for other works by this author on: GSW Google Scholar George Y. Chao George Y. Chao Carleton University, Canada Search for other works by this author on: GSW Google Scholar American Mineralogist (1997) 82 (11-12): 1255–1260. https://doi.org/10.2138/am-1997-11-1220 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Joel D. Grice, George Y. Chao; Lukechangite-(Ce), a new rare-earth-fluorocarbonate mineral from Mont Saint-Hilaire, Quebec. American Mineralogist 1997;; 82 (11-12): 1255–1260. doi: https://doi.org/10.2138/am-1997-11-1220 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Lukechangite-(Ce), ideally Na3Ce2(CO3)4F, is a new mineral from Mont Saint-Hilaire, Quebec. It occurs as tabular, short prismatic, and barrel-shaped crystals up to 1 mm. It is colorless to pale beige with a white streak and a vitreous, or somewhat pearly on {0001}, luster. Associated minerals include microcline, analcime, sodalite, aegirine, serandite, eudialyte, catapleiite, fluorite, petersenite-(Ce), siderite, astrophyllite, and albite. Lukechangite-(Ce) is soft, Mohs hardness ≈ 4½, brittle, with an uneven to conchoidal fracture, and with perfect {0001} cleavage. Lukechangite-(Ce) is uniaxial negative, ω = 1.728(3) and ϵ = 1.542(1). It is hexagonal, space group P63/mmc, a = 5.068(1), c = 22.87(5) Å, V = 509(1) Å3, and Z = 2. The strongest X-ray powder diffraction lines [d (Å), I, hkl] are: 5.71(50)(004), 4.31(100)(101), 3.804(50)(006), 3.169(70)(105), 2.877(60)(106), 2.534(70)(110), 2.192(90B)(109,200,201), 1.978(70)(205), and 1.658(50)(209,210,211). An average of the electron-microprobe analyses gave Na2O 14.94, CaO 0.10, SrO 0.12, La2O3 16.36, Ce2O3 29.48, Pr2O3 1.95, Nd2O3 5.88, F 3.58, CO2 (28.40), and O ≡ F – 1.51, total 99.30 wt%. CO2 was calculated by stoichiometry from the results of the crystal-structure analysis. Dcalc is 4.02 g/cm3. The atomic arrangement of lukechangite-(Ce) has been refined to R = 3.4%. The structure is layered parallel to (001), with CO3 groups oriented parallel to the layering forming thick slabs incorporating either Ce or Na cations and a separate Na-F layer. The structure of lukechangite-(Ce) resembles that of huanghoite-(Ce) and baiyuneboite-(Ce) and is isostructural with synthetic Na3La2(CO3)4F. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.