TY - JOUR

T1 - Ln3+ (Ln3+ = La, Nd, Eu, Yb) incorporation in synthetic tourmaline analogues: Towards tourmaline REE pattern explanation

AU - Vereshchagin, Oleg S.

AU - Britvin, Sergey N.

AU - Wunder, Bernd

AU - Frank-Kamenetskaya, Olga V.

AU - Wilke, Franziska

AU - Vlasenko, Natalia S.

AU - Shilovskikh, Vladimir V.

AU - Bocharov, Vladimir N.

AU - Danilov, Denis V.

N1 - Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/12/5

Y1 - 2021/12/5

N2 - Tourmaline rare-earth element (lanthanides + Y) patterns could provide valuable geological information as tourmalines are the most abundant borosilicates on Earth and are stable at extreme PT conditions. The lanthanide-bearing tourmalines were synthesized for the first time in a series of high- (4 GPa) and low-pressure (0.2 GPa) hydrothermal experiments. We have found that Ln-content (Ln = La 3+, Nd 3+, Eu 3+ and Yb 3+) in synthetic tourmalines varies significantly (1.13–8.35 wt% Ln 2O 3) with Yb < La ≤ Nd < Eu independent of pressure conditions. Ln-content in synthetic tourmalines, obtained at low pressure is 2–3 times higher, than those from high-pressure experiments. The Nd- and Eu-rich synthetic tourmalines exhibit cathodo- photoluminescence properties (blue and violet luminescence colors for Nd and Eu, respectively), which confirms trivalent state of Ln in tourmaline structure. Single-crystal X-ray diffraction data for synthetic tourmalines (Nd-rich a 15.893(1), c 7.130(1) Å; Eu-rich a 15.903(5), c 7.168(3) Å) show that Eu 3+ and Nd 3+ occupy the 9-coordinated X-site in the tourmaline structure. The general formula of obtained synthetic tourmalines can be expressed as Ln 3+ 1-x (Mg,Al) 3 (Al,Mg) 6 (Si 6O 18) (BO 3) 3 (OH,O) 3 (OH,O) (0.05 ≤ x ≤ 0.97). The crystal-chemical features and lanthanide speciation in synthesized tourmalines are herein discussed and compared to natural and synthetic compounds.

AB - Tourmaline rare-earth element (lanthanides + Y) patterns could provide valuable geological information as tourmalines are the most abundant borosilicates on Earth and are stable at extreme PT conditions. The lanthanide-bearing tourmalines were synthesized for the first time in a series of high- (4 GPa) and low-pressure (0.2 GPa) hydrothermal experiments. We have found that Ln-content (Ln = La 3+, Nd 3+, Eu 3+ and Yb 3+) in synthetic tourmalines varies significantly (1.13–8.35 wt% Ln 2O 3) with Yb < La ≤ Nd < Eu independent of pressure conditions. Ln-content in synthetic tourmalines, obtained at low pressure is 2–3 times higher, than those from high-pressure experiments. The Nd- and Eu-rich synthetic tourmalines exhibit cathodo- photoluminescence properties (blue and violet luminescence colors for Nd and Eu, respectively), which confirms trivalent state of Ln in tourmaline structure. Single-crystal X-ray diffraction data for synthetic tourmalines (Nd-rich a 15.893(1), c 7.130(1) Å; Eu-rich a 15.903(5), c 7.168(3) Å) show that Eu 3+ and Nd 3+ occupy the 9-coordinated X-site in the tourmaline structure. The general formula of obtained synthetic tourmalines can be expressed as Ln 3+ 1-x (Mg,Al) 3 (Al,Mg) 6 (Si 6O 18) (BO 3) 3 (OH,O) 3 (OH,O) (0.05 ≤ x ≤ 0.97). The crystal-chemical features and lanthanide speciation in synthesized tourmalines are herein discussed and compared to natural and synthetic compounds.

KW - Crystal chemistry

KW - End-member

KW - Geochemistry

KW - REE

KW - Synthesis

KW - Tourmaline

UR - http://www.scopus.com/inward/record.url?scp=85115953693&partnerID=8YFLogxK

U2 - 10.1016/j.chemgeo.2021.120526

DO - 10.1016/j.chemgeo.2021.120526

M3 - Article

VL - 584

SP - 120526

JO - Chemical Geology

JF - Chemical Geology

SN - 0009-2541

M1 - 120526

ER -