biotite

The granite in the complex is mainly composed of alkali feldspar, quartz, Plagioclase, muscovite and biotite. Magnetite and sphene occurs are also associated in minor quantities.

The main rock-forming minerals of gneisses (in%) are plagioclase (47-65), biotite (11-42) and quartz (0.7-24).

Sector-hourglass zoning--Sector-hourglass zoning typically occurs in chloritoid, and less commonly in biotite and staurolite (Fig.

However, Chen et al [9] reported significant improvements in the digestibility of Ca and P as a result of supplementation with either 1% or 2% Biotite V (aluminosilicate clay).

The metamorphic rocks of the Silgara Formation in the Santander Massif (Figure 1) were metamorphosed to upper amphibolites facies during the Caledonian orogeny, developing a sequence of metamorphic zones (biotite, garnet, staurolite and sillimanite) that defines the regional thermal structure.

The foliation was caused mainly by biotite grain arrangement.

The metamorphic mineral assemblage in most of the pelitic rocks consists of chlorite, muscovite, biotite, and albitic plagioclase whereas in the Whycocomagh Mountain area the grade is higher and garnet and andalusite are present.

In places it showed wavy flow structures, and also present were a few primary magmatic inclusions such as plagioclase (up to 1.3 mm) and altered greenish brown biotite platelets (0.5-1.6 mm; Figure 13a).

The studied granodiorite sample (Vlc-2-2) is made up of coarse-grained plagioclase, hornblende, biotite, quartz and microperthitic feldspar.

Micas: To this group, we assigned individual crystals of biotite and muscovite as well as crystals of these minerals in phaneritic rock fragments.