A major role of phlogopite
, instead of amphibole, is recognised for their mantle source (Ubide et al, 2011).
Our data do not provide a definitive answer to that question, which would require more petrological studies and/or geochronology, but the [sup.40]Ar/[sup.39]Ar cooling age of 421 [+ or -] 4 Ma for phlogopite
in a gabbroic unit in the Moosehorn Plutonic Suite suggests that it is more likely the Baring Granite.
The crystals are of two types: "mica schist-hosted" crystals are heavily infused with dark phlogopite
and tend to be blackish, at least in their outer zones, resembling old Russian emerald crystals; "quartz-hosted" emeralds occur in very rare pockets and, more commonly, in boudin structures which have been flooded with silica.
Premium grades of highly pure, low-iron, platy talcs, high-purity calcium carbonates, phlogopite
micas, and ground white barium sulfate for high-density compounds.
This may reflect retention of Rb in phlogopite
at low percentages of melting (highest Sr rocks).
Significantly, evolved phlogopite
lamproite tuffs, which typically have reduced diamond potential, are absent from all cores recovered.
mica is an excellent glass extender in glass-filled nylon and polyolefins.
In fact, 1990 output was 6.8 Mt of ore and 1.4 Mt of waste for the production of 546,134 t of apatite concentrate, 97,852 t of agricultural lime and 4,763 t of phlogopite
This is a monomineral rock composed of calcite, with occasional phlogopite
4c and d).The volcanics in Bhm where least altered are petrographically basanite and alkali- basalt contain phenocrysts of olivine and augite with a groundmass consisting of plagioclase, pargasite, phlogopite
and opaque and glassy material.
In both modes of occurrence, its composition is intermediate between phlogopite
and annite, with relatively low aluminum content, and it plots in the field for calc-alkalic orogenic suites in the ternary MgO-Fe[O.sup.t]-[Al.sub.2][O.sub.3] discrimination diagram (Fig.
Several of his specimens were illustrated in the 6th edition of Dana's System of Mineralogy--for example, phlogopite
form Clark's Hill, St.