The Martha's Vineyard Land Bank recently bought 31 acres of rare land at Tom's Neck Farm, the culmination of a complicated deal involving multiple sellers, local donors and a financing model that marks a first for the land bank.

A key piece of historic coastal farmland on Chappaquiddick will be conserved, thanks to a purchase announced this week by the Martha’s Vineyard Land Bank.

The land bank said Wednesday that it had signed a contract to buy 25 acres of the former Tom’s Neck Farm off the Dike Bridge Road. The purchase price is $5.175 million.