1. Aplite () is an intrusive igneous rock that has a granitic composition. Aplites are fine-grained to aphanitic (without grains visible to the naked eye) and may consist of only quartz and feldspar or the term may refer to any leucocratic (pale-coloured) minor intrusion of that grain size. They are associated with the later stages of many larger intermediate to felsic intrusions. == Occurrence == Aplites have a global distribution and have been described from most areas where there are significant granitic intrusions. They occur in the form of intrusive sheets, both within the associated granitic bodies and in the surrounding country rock. Trace element analysis shows that there are no volcanic equivalents to aplites. Some aplites form in close association with pegmatites, which are otherwise uncommon in granites. These aplite-pegmatite sheet complexes may show fine-scale banding with alternations of aplite and pegmatite. Syenite-aplites consist mainly of alkali feldspar; the diorite-aplites... from wikipedia.org