Borolanite is an historical petrological name for a pyroxene-melanite bearing nepheline syenite variety which contains nepheline-alkali feldspar pseudomorphs interpreted to be after leucite which occur as conspicuous white spots in the dark rock matrix.
In this locality there is a considerable area of granite rich in red alkali feldspar, and passing, by diminution in the amount of its quartz, into quartz-syenites and syenites.
The abundance of melanite is very unusual in igneous rocks, though some syenites, leucitophyres, and aegirine-felsites resemble borolanite in this respect.
In places the nepheline syenite assumes the form of a dark rock with large rounded white spots.
In Finland, melanite bearing nepheline rocks have been found and described as ijolite, but the only other locality for melanite-leucite-syenite is Magnet Cove igneous complex in Arkansas.