AbstractThe normative mineralogy of the Loch Borralan, Loch Ailsh and Loch Loyal leucosyenites is compared to the System Ab – Or – An ‐ Qz. At Borralan, the upper quartz‐syenites of Cnoc‐na‐Sroine plot within the plagioclase volume, the lower perthosites within the alkali feldspar volume. This mineralogy cannot have been attained byin situcrystal fractionation. The Ailsh rocks plot within the plagioclase volume, the Loyal syenites within the alkali feldspar volume. The three complexes cannot have been derived from a single magma body at depth, and are not preci