The Goulding–Keene pegmatite consists essentially of albite, nepheline, and biotite with minor amounts of microline and other minerals. It is enclosed by plagioclase–nepheline–biotite–hastingsite–calcite gneisses and is apparently intrusive into these gneisses since it cuts the foliation of the gneisses, has some sharp contacts, and is not itself foliated. The gneisses and the pegmatite were sampled by more than 240 m of diamond drill core. Rock and mineral analyses show that the present composition of the pegmatite is very unlikely to be an igneous composition, and therefore that metasomatism has changed the original composition after emplacement of the pegmatite as a melt. This is consistent with textures observed in the gneisses and pegmatite.