A boron-rich serpentine (Ranorosoa et al., 1989), often confused with a boron-rich chlorite in older literature. Manandonite has an ideal chemical composition of Li₂Al₄(Si₂AlB)O₁₀(OH)₈ and occurs in the 2H₂ polytype. Manandonite occurs in the Antandrokomby pegmatite, Manadona River, near Antsirabe, Madagascar.
Cf., borocookeite, boromuscovite