First find of ferropseudobrookite in quartz from Napier Complex, East Antarctica
Miyake, Akira; Hokada, Tomokazu
published: Feb 1, 2013
ArtNo. ESP147052501005, Price: 29.00 €
Ferropseudobrookite exsolution rods, approximately Mg2+0.11Fe2+0.70Al3+0.04Fe3+0.34Ti4+1.81O5,space group Cmcm with a about 0.98 nm, b about 0.37 nm, c about 1.00 nm, are first reported in quartz from a garnet-orthopyroxene-bearing quartzofeldspathic gneiss, Napier Complex, East Antarctica. The elongated direction of ferropseudobrookite rods is the b axis and is parallel to either the or of low-quartz. Moreover these rods have almost six-fold symmetry along the c axis of quartz. The formation of the exsolution must result from the cooling of the gneiss and the exsolution took place in the high-quartz field. The present exsolution phenomenon suggests that quartz can dissolve not only Ti but also Fe2+and Fe3+ and that the gneiss contains Fe2+ ion under the ultrahigh-temperature peak metamorphic conditions.