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)
A black tourmaline sample from Seagull batholith (Yukon Territory, Canada) was established to be a schorl with concentrations of Fe2+ among the highest currently found in nature (FeOtot ~ 18 wt.% and Fe2+ ~ 100% of Fetot) on the basis of a multi-analytical characterization through Mössbauer spectroscopy, electron microprobe, Laser-Ablation Inductively-Coupled-Plasma Mass-Spectrometry and single-crystal X-ray diffraction.