Discussions

💬 Home 🔎 Search 📅 Latest

╳Discussions

💬 Home 🔎 Search 📅 Latest

Groups

Recent Images in Discussions

Mineralogical ClassificationVästmanlandite-(Ce): abstract

10th Apr 2005 19:53 UTCMarco E. Ciriotti

Västmanlandite-(Ce) = IMA 2002-025: reference and abstract.

• Holtstam, D., Kolitsch, U., Andersson, U.B. (2005): Västmanlandite-(Ce) – a new lanthanide- and F-bearing sorosilicate mineral from Västmanland, Sweden: description, crystal structure, and relation to gatelite-(Ce). European Journal of Mineralogy, 17, 129-142.

Abstract:

Västmanlandite-(Ce), ideally (Ce,La)3CaAl2Mg23F(OH)2, is a new mineral species from the Västmanland county, Bergslagen region, Sweden. Together with more Fe-rich, F-poor members, it forms solid solutions that are important for lanthanide sequestration in the Bastnäs-type skarn deposits in Västmanland. At the type locality (Malmkärra, Norberg district) it occurs as anhedral grains 0.2–3 mm across, in association with fluorbritholite-(Ce), tremolite, a serpentine mineral, magnetite, dollaseite-(Ce) and dolomite. The mineral is allanite-like in appearance; it is dark brown, translucent, with vitreous luster, and has good cleavage parallel to {001}, uneven to conchoidal fracture, and a yellowish gray streak; Dcalc = 4.51(2) g·cm-3 and Mohs hardness 6. Optically it is biaxial (–), with = 1.781(4), calc = 1.792, = 1.810(4) and 2V = 75(5)°. Chemical analysis by electron-microprobe and 57Fe Mössbauer spectroscopy yield: La2O3 13.65, Ce2O3 23.90, Pr2O3 2.07, Nd2O3 6.28, Sm2O3 0.42, Gd2O3 0.15, Y2O3 0.18, CaO 4.65, FeO 1.14, Fe2O3 2.69, MgO 5.51, Al2O3 8.58, TiO2 0.04, P2O5 0.05, SiO2 26.61, F 1.06, H2Ocalc 1.61, O = F –0.45, sum 98.14. Västmanlandite-(Ce) is monoclinic, P21/m, with a = 8.939(1), b = 5.706(1), c = 15.855(2) Å, = 94.58(1)°, V = 806.1(2) Å3, and Z = 2 (single-crystal data). The eight strongest lines in the X-ray powder diffraction pattern are : 15.81(16)(001), 4.65(10)(111), 3.50(20)(210), 2.983(100)(114), 2.685(13)(121), 2.678(11)(205), 2.625(19)(311), and 2.187(15)(402). The crystal structure was determined using single-crystal X-ray diffraction data and refined to R1(F) = 1.73 % for 2864 'observed' reflections with Fo > 4(Fo). Västmanlandite-(Ce) is nearly isotypic to gatelite-(Ce), ideally Ce3 CaAl2AlMg3O(OH)2, and can be described as a regular dollaseite-(Ce)–törnebohmite-(Ce) polysome. The occurrence of extremely weak, continuous streaking in the diffraction patterns, and the presence of two pairs of mirror-related atoms in the törnebohmite-(Ce) module indicate that the structure model represents an average structure, unlike the situation in gatelite-(Ce) where there are no continuous streaks but instead, due to atomic ordering, sharp superstructure reflections resulting in a different unit cell.

11th Apr 2005 16:06 UTCUwe

Anyone interested in the full paper can be a PDF reprint from me.

Cheers, Uwe

12th Apr 2005 11:32 UTCPeter Haas

Västmanlandite-(Ce) has been added to the database. I noticed that gatelite-(Ce) was missing as well and I added the name and the formula. I would appreciate it when someone could provide more data about the latter.

12th Apr 2005 17:36 UTCUwe

Should read of course:

Anyone interested in the full paper can get a PDF reprint from me.

Uwe

Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: May 9, 2024 21:37:47

Go to top of page