Rather large vein in biotite schists about 1.5 to 2 m thick. Emerald
is usually located near the contact of the pegmatite with schists. Towards the center of the vein, beryl
becomes pale and changes to aquamarine
and white or yellow beryl
. Small emerald crystals, closely intergrown with feldspars, were mined as "emerald matrix".
Ref: E.Ya. Kievlenko, Geology of gems, 2003, p. 79