almandine UK /ˈal.mən.dʌɪn/US /ˈæl.mənˌdin/ noun1 •A type of garnet having a deep red color, inclining to purple, with the chemical formula Fe₃Al₂(SiO₄)₃.Almandine, the variety found here, is stable at temperatures of 540 to 900°C at a pressure of 200 GPa. — 2004 formsalmandines