Under opbygning

The Wiborg rapakivi granite batholith in southeastern Finland con-tains six anorthosite areas ranging from 0.1 to 1.5 km2. Five of them are located at the contacts between wiborgite and even-grained rapa-kivi granite. In this study the anorthosites are comprehended as large inclusions within the rapakivi batholith. Plagioclase (An50–70) in the anorthosite iridesces strongly in spectral colours, and is thus known as spectrolite. It is used as a precious and a dimension stone. In this study, the contacts of the anorthosite bodies, rock types, their mu-tual relations and general petrographic features are described based on field work and thin sections. Insight is given into the utilization of spectrolite in terms of its quantity and quality in different rock types. Among the rock types in the anorthosite inclusions, leuco-gabbronorite has the highest potential to be utilized, because it is the most common ma舀c rock type in the inclusions and contains the most spectrolite. In addition, spectrolite is well distinguished within it, because the crystals are large and leucogabbronorite is the darkest rock type in the area.