Crystal-chemical behavior of Fe2+ in tourmaline dictated by structural stability: insights from a schorl with formula NaY(Fe2+2Al)Z(Al5Fe2+)(Si6O18)(BO3)3(OH)3(OH,F) from Seagull batholith (Yukon Territory, Canada)

Andreozzi, Giovanni B.; Bosi, Ferdinando; Celata, Beatrice; Capizzi, Luca S.; Stagno, Vincenzo; Beckett-Brown, C E

doi:10.1007/s00269-020-01094-7

Cited by 9 publications

(3 citation statements)

References 40 publications

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“…Tourmaline is one of the most fascinating and colourful accessory mineral occurring in a variety of geological environments, from diagenetic stages to granulite facies grade (e.g., Henry and Dutrow 1996;Dutrow and Henry 2011;Bosi et al 2018aBosi et al , 2019aAndreozzi et al 2020).…”

Section: Introductionmentioning

confidence: 99%

In situ high-temperature behaviour of fluor-elbaite: breakdown conditions and products

et al. 2021

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The thermal behaviour of a fluor-elbaite from Minas Gerais (Brazil) was investigated at room pressure through in situ high-temperature X-ray powder diffraction (HT-XRPD), until the breakdown conditions were reached. The variations of fluor-elbaite structural parameters (unit-cell parameters and mean bond distances) were monitored together with site occupancies, and two main internal reactions were identified: the thermally-induced Fe oxidation process counterbalanced by (OH)– deprotonation, which starts at 500 °C (773 K), followed by a partial intracrystalline Fe–Al exchange between the octahedrally-coordinated Y and Z sites. The fluor-elbaite breakdown reaction occurs between 850 °C (1123 K) and 900 °C (1173 K). The breakdown products were identified at room temperature by XRPD and the breakdown reaction can be described by the following reaction: tourmaline → B-bearing mullite + hematite + spinel + B-poor (Na, Li, H2O)-bearing glass. Boromullite itself was not observed in the final heating products, and the B-bearing mullite from the breakdown reaction exhibited unit-cell parameters a = 7.5382(2) Å, b = 7.6749(2) Å, c = 2.8385(1) Å, V = 164.22(1) Å3 (space group Pbam) consistent with an approximate Al8.5B1.5Si2O19 composition.

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Section: Introductionmentioning

confidence: 99%

In situ high-temperature behaviour of fluor-elbaite: breakdown conditions and products

et al. 2021

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“…Tourmaline minerals are complex borosilicates that have been studied extensively in terms of their crystal structure and crystal chemistry (e.g. Foit, 1989; Grice and Ercit, 1993; Ertl et al , 2002; Novák et al , 2004; Bosi and Lucchesi, 2007; Bosi 2013, 2018; Novák et al , 2011; Henry and Dutrow, 2011; Henry et al , 2011; Cempírek et al , 2013; Ertl et al , 2018; Andreozzi et al , 2020).…”

Section: Introductionmentioning

confidence: 99%

Mn-bearing purplish-red tourmaline from the Anjanabonoina pegmatite, Madagascar

Bosi

Celata

Skogby

et al. 2021

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A gem-quality purplish-red tourmaline sample of alleged liddicoatitic composition from the Anjanabonoina pegmatite, Madagascar, has been fully characterised using a multi-analytical approach to define its crystal-chemical identity. Single-crystal X-ray diffraction, chemical and spectroscopic analysis resulted in the formula: X(Na0.41□0.35Ca0.24)Σ1.00Y(Al1.81Li1.00Fe3+0.04Mn3+0.02Mn2+0.12Ti0.004)Σ3.00ZAl6 [T(Si5.60B0.40)Σ6.00O18] (BO3)3 (OH)3W[(OH)0.50F0.13O0.37]Σ1.00 which corresponds to the tourmaline species elbaite having the typical space group R3m and relatively small unit-cell dimensions, a = 15.7935(4) Å, c = 7.0860(2) Å and V = 7.0860(2) Å3. Optical absorption spectroscopy showed that the purplish-red colour is caused by minor amounts of Mn3+ (Mn2O3 = 0.20 wt.%). Thermal treatment in air up to 750°C strongly intensified the colour of the sample due to the oxidation of all Mn2+ to Mn3+ (Mn2O3 up to 1.21 wt.%). Based on infrared and Raman data, a crystal-chemical model regarding the electrostatic interaction between the X cation and W anion, and involving the Y cations as well, is proposed to explain the absence or rarity of the mineral species ‘liddicoatite’.

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“…2) of the Al-V-Cr-Fe 3+ quaternary system is used (Henry et al, 2011). This diagram is based on occupancy of the Z site obtained from the tourmaline ordered formula, which also removes issues of uncertainty associated with order-disorder across the Y and Z sites as may occur for example between Fe 2+ -Al in schorl (Andreozzi et al, 2020). In other words, the use of the diagrams in Figures 1 and 2 is equivalent to classifying tourmalines using only the chemical information of the Y and Z sites.…”

Section: Discussionmentioning

confidence: 99%

Chromium-rich vanadio-oxy-dravite from the Tzarevskoye uranium–vanadium deposit, Karelia, Russia: a second world-occurrence of Al–Cr–V–oxy-tourmaline

Bosi

Altieri

Cámara

et al. 2020

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Crystal-chemical behavior of Fe2+ in tourmaline dictated by structural stability: insights from a schorl with formula NaY(Fe2+2Al)Z(Al5Fe2+)(Si6O18)(BO3)3(OH)3(OH,F) from Seagull batholith (Yukon Territory, Canada)

Cited by 9 publications

References 40 publications

In situ high-temperature behaviour of fluor-elbaite: breakdown conditions and products

In situ high-temperature behaviour of fluor-elbaite: breakdown conditions and products

Mn-bearing purplish-red tourmaline from the Anjanabonoina pegmatite, Madagascar

Chromium-rich vanadio-oxy-dravite from the Tzarevskoye uranium–vanadium deposit, Karelia, Russia: a second world-occurrence of Al–Cr–V–oxy-tourmaline

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