Occurrence of Difluorine F₂ in Nature—In Situ Proof and Quantification by NMR Spectroscopy

Abstract

The most reactive chemical element, F(2), has been claimed not to occur in nature. First direct evidence from in situ NMR spectroscopy now proves that elemental F(2) indeed occurs in nature as an occlusion in "antozonite" (right in the picture), a variant of fluorite (CaF(2), left).

Naturally irradiated fluorite as a historic violet pigment: Raman spectroscopic and X‐ray diffraction study

“…This type of irradiated fluorite is commonly called antozonite, or fetid fluorite (derived from the specific odour that antozonite emanates when crushed). The nature of the odour has been discussed by several authors; while Vochten et al (1977) reported that the enclosed gases comprised of SO 2 , SOF 2 , S 2 F 2 , H 2 S and Ar, the most recent study by Schmedt auf der Günne et al (2012) showed that based on olfactory testing and magic‐angle‐spinning nuclear magnetic resonance (MAS‐NMR) spectroscopy analysis, the odour is caused by elemental difluorine. These intensely coloured fluorites are often banded with less‐saturated or almost colourless parts.…”

Trace Determination and Pressure Estimation of Fluorine F2 Caused by Irradiation Damage in Minerals and Synthetic Fluorides

“…The trace determination of F 2 in the mineral Villiaumite by 19 F NMR is the second piece of direct evidence for elemental fluorine in nature. We speculate that its formation must also derive from the effects of radiation arising from nearby radioactive minerals, as in the case of the mineral „Antozonite“, in which elemental fluorine in nature was detected for the first time …”

“…The formation of micron‐sized F 2 bubbles has already been observed in CaF 2 by atomic force microscopy, in which the pressure of the F 2 fluid was estimated to be around 50 MPa . The occurrence and quantification of F 2 in the natural mineral „Antozonite“, a variant of fluorite, suggested its occlusions originate from natural radioactivity . Recently, attention has been drawn to the stability of polyfluoride anions and the existence of F 5 − in a neon matrix …”

Introduction

“…Even elemental fluorine (F 2 ) occurs in Nature, as an inclusion in fluorspar (about 0.46 mg of F 2 per gram of CaF 2 ). The so-called ''stinkspar'' or ''antozonite,'' which has been irradiated with γ -radiation from uranium ore, releases a pungent smell on rubbing or crushing [23].…”