Chambersite is a manganese borate mineral with formula:Mn₃B₇O₁₃Cl. It is a member of the borate mineral series that includes other minerals such as ericacite, Fe₃B₇O₁₃Cl, and boracite Mg₃B₇O₁₃Cl. When chambersite was first discovered, it was the second chemical analogue of boracite to be found in nature. It was discovered as a mineral at Barber's Hill salt dome in Texas in 1957 and in 1971 at the Dongshuichang deposit in Jixian, Tianjin, China. Chambersite occurs associated with the evaporite minerals halite, anhydrite, and gypsum.