Microdistribution of boron: particle‐track images from samples of a Caledonian igneous complex

⁷Li recoil tracks in Lexan^R formed as a product of irradiation with thermal neutrons give an image of in sifu‐microdistribution of boron in dioritic to granitic rocks of the Caledonian Ballachulish zoned complex and in a carbonate rock from its contact aureole. The images exhibit a polyphase incorporation of boron into primary and secondary minerals. The boron microdistribution is inhomogeneous. Isomorphous incorporation of boron into pyroxene and plagioclase during the main stage of crystallization cannot be established, because the boron distribution is blurred by secondary alteration. In contrast to the intracrystalline feature, the crystal interfaces are enriched in boron. Increased concentrations are also disclosed by overgrowths of primary crystals, exsolution lamellae in alkali feldspar and alteration rims of clinopyroxene. The highest amounts of boron in a siliceous dolomite marble of the contact aureole are found in the alteration products of olivine.