Definition of chloritoid in US English:



  • A greenish-gray or black mineral resembling chlorite, found in metamorphosed clay sediments. It consists of a basic aluminosilicate of iron, often with magnesium.

    • ‘A very low-grade metamorphism, which developed chloritoid, affects cleaved rocks.’
    • ‘In contrast to South Achill, peliticlithologies are characterized by the virtual absence of prograde chlorite and chloritoid, whereas biotite is significantly more abundant.’
    • ‘In the Messaria nappe, kyanite and chloritoid in weakly sheared rocks have cracks that are filled with chlorite and quartz.’
    • ‘Pyrite, garnets (partially chloritized), talc, magnetite, molybdenite, and chloritoid also commonly occur.’
    • ‘The phyllites show fine-grained foliated textures and the mineral assemblage consists of chlorite, muscovite, albite, chloritoid and garnet along the main foliation.’