Flakes of white mica were on the line between muscovite and phengite
. Chlorite flakes generally contained traces of titanium and potassium, strongly suggesting that chlorite derived from biotite alteration.
The blueschist facies comprise of sodic amphibole + garnet + phengite
+ lawsonite and/or epidote [+ or -] omphacite [+ or -] quartz characterizing a broad range of pressure-temperature conditions (12-16 kbar, 380-500 [degrees]C) (Okay, 2002).
The tectonic significance of pre-Scandian [sup.40]Ar/[sup.39]Ar phengite
cooling ages in the Caledonides of western Norway.
The content of phengite
component is therefore very low.
The composition of the white-mica is muscovite to phengite
(Willner et al., 2012).
Analyses of the multiequilibrium between chlorite and phengite
solide solution following Lanari et al (2010) method, allow the estimation of metamorphic conditions at 400degC for 5 Kbar for this last event.
In addition, and whilst not a definitive metallurgical study, Dr Halley's work indicated that gold is depleted in the upper oxide area and enriched in the lower oxide to fresh rock transition, and the strongest mineralised zones are also depleted in calcium in phengitic altered zones (phengite
is a greenish potassium magnesium mica mineral).
These cavities are partially filled with chlorite, Mg-celadonite, illite, phengite
micas or quartz.
1.53 0.01 0.31 9.92 Phengite
S68-l33 49.54 0.04 28.86 1.77 n.d.
There is a high percentage of calcite clasts, which were cemented with a phengite