Synthesis of fluorphlogopite single crystals. Applications to experimental studies
Hammouda, Tahar; Pichavant, Michel; Barbey, Pierre; Brearley, Adrian J.
European Journal of Mineralogy Volume 7 Number 6 (1995), p. 1381 - 1388
published: Dec 27, 1995
manuscript accepted: Jun 20, 1995
manuscript received: Aug 23, 1994
ArtNo. ESP147050706011, Price: 29.00 €
Abstract We describe a practical method of synthesis of fluorphlogopite single crystals suited to common laboratory conditions. The 1-atm batch melting technique was adapted using starting compositions having a slight excess of fluorine, added as K2SiF6. The oxide-fluoride mixture was melted above the liquidus temperature and then cooled at a rate of a few degrees per hour between 1400 and 1300°C. Large (millimetre- to centimetre-size), clear and detachable single crystals were obtained by adding a quench of the charge during the cooling stage. XRD, TEM and electron microprobe analyses confirm that the micas produced are mostly monoclinic 1M polytypes having chemical compositions very close to the end-member fluorphlogopite. Heating experiments confirm that melting of fluorphlogopite is congruent. From both heating experiments and thermal analysis, the melting temperature of fluorphlogopite is located at values ≥ 1390°C. Synthetic fluor-mica single crystals are of practical interest as analytical standards, and for several applications in experimental petrology