Large metamorphic minerals (e.g., porphyroblasts
such as biotite, garnet, andalusite and staurolite) that contain passive inclusions are extraordinarily important because they are utilized in assessing the tectonic, metamorphic, and structural history of the mid- to deep-crustal levels of orogenic belts.
They show jointing and intense fracturing, deformation and deflection of the main foliation of the rock around most garnet porphyroblasts
. In some cases, a strong mylonitic deformation evidenced by lengthening and stretching of quartz, among others, is observed.
The late schistosity in the sedimentary rocks, defined by muscovite and biotite, wraps around cordierite porphyroblasts
, which contain relicts of the earlier phyllitic cleavage (Thorne and Lentz 2001; Park et al.
Staurolite forms honey-brown large prismatic porphyroblasts
which quite frequently reach up to 1.2 cm across and 12 cm in length, elongated along the schistosity and usually displaying reaction rims.
They show porphyroblasts
of quartz, muscovite and oxide phases.
The amphibolite is porphyroblastic and contains porphyroblasts
Albite (Ab) and Grt2 (mineral abbreviations from Whitney and Evans, 2010) are porphyroblasts
mainly syn-kinematic with the S2 and frequently helicitic, including a previous foliation (S1) (Figs.
The graphite occurs within "fairly homogeneous, quartz-graphite schist, incorporating minor "porphyroblasts
" of muscovlte crystals and small lenses of extremely fine sillimanite".
and Speck, P.J.H.R.: 1994, The kinematic interpretation of obliquely-transected porphyroblasts
: an example from the Trois Seigneurs Massif, France, J.
GROWTH OF CENTIMETER-SCALE GARNET PORPHYROBLASTS
Andalusite, and rarely cordierite, porphyroblasts
Migmatization is widespread, resulting in the formation of plagioclase and potassium-feldspar porphyroblasts
and occasionally charnockitic leucosomes, also of small granitoid veins and bodies.