TY - JOUR

T1 - Incorporation of 3d elements in tourmalines

T2 - Structural adjustments and stability

AU - Vereshchagin, Oleg S.

AU - Frank-Kamenetskaya, Olga V.

AU - Rozhdestvenskaya, Ira V.

AU - Zolotarev, Anatoly A.

PY - 2018/9/1

Y1 - 2018/9/1

N2 - The crystal structure of 45 tourmalines containing trivalent cations (Me3+: Cr3+, V3+, Fe3+) and 43 tourmalines containing divalent cations (Me2+: Fe2+, Mn2+, Co2+, Ni2+, Cu2+) of 3d elements were analysed. We establish that the incorporation of Me3+ cations is controlled by the ratio between the sizes of YO6 and ZO(6) octahedra and does not exceed eight atoms per formula unit (apfu), while the incorporation of Me2+ cations is controlled by the charge balance and does not exceed 3 apfu. We prove that there are no structural constraints controlling the incorporation of Co, Ni and Cu cations into the tourmaline structure at concentrations of up to 1 apfu. We show that, when the limiting content (less or equal to 1 apfu and 1.6 apfu for divalent and trivalent cations, respectively) is reached, these cations start to occupy not only YO6, but also ZO(6) octahedra, to maintain stability of the crystal structure. As the content of 3d-element cations increases further, the degree of disorder grows and, at a content of similar to 7 apfu, their distribution is close to statistical. An increase in the content of 3d cations, accompanied by their disordering, causes a decrease in disparity between sizes of YO6 and ZO(6) octahedra and their deformations.

AB - The crystal structure of 45 tourmalines containing trivalent cations (Me3+: Cr3+, V3+, Fe3+) and 43 tourmalines containing divalent cations (Me2+: Fe2+, Mn2+, Co2+, Ni2+, Cu2+) of 3d elements were analysed. We establish that the incorporation of Me3+ cations is controlled by the ratio between the sizes of YO6 and ZO(6) octahedra and does not exceed eight atoms per formula unit (apfu), while the incorporation of Me2+ cations is controlled by the charge balance and does not exceed 3 apfu. We prove that there are no structural constraints controlling the incorporation of Co, Ni and Cu cations into the tourmaline structure at concentrations of up to 1 apfu. We show that, when the limiting content (less or equal to 1 apfu and 1.6 apfu for divalent and trivalent cations, respectively) is reached, these cations start to occupy not only YO6, but also ZO(6) octahedra, to maintain stability of the crystal structure. As the content of 3d-element cations increases further, the degree of disorder grows and, at a content of similar to 7 apfu, their distribution is close to statistical. An increase in the content of 3d cations, accompanied by their disordering, causes a decrease in disparity between sizes of YO6 and ZO(6) octahedra and their deformations.

KW - tourmaline

KW - structural adjustment

KW - crystal structure refinement

KW - crystal chemistry

KW - 3d elements

KW - SCHORL-DRAVITE SERIES

KW - MN2+ SITE OCCUPANCY

KW - CRYSTAL-STRUCTURE

KW - BEARING TOURMALINES

KW - MN2+-RICH TOURMALINE

KW - NICKELOAN TOURMALINE

KW - CHEMICAL-COMPOSITION

KW - RICH TOURMALINE

KW - SOLID-SOLUTIONS

KW - GOLD DEPOSIT

UR - http://www.scopus.com/inward/record.url?scp=85056568204&partnerID=8YFLogxK

U2 - 10.1127/ejm/2018/0030-2781

DO - 10.1127/ejm/2018/0030-2781

M3 - Article

AN - SCOPUS:85056568204

VL - 30

SP - 917

EP - 928

JO - European Journal of Mineralogy

JF - European Journal of Mineralogy

SN - 0935-1221

IS - 5

ER -