(IDEX Online) - Two senior members of Lucara's management team are stepping down, days after the Canadian miner walked away from its sales agreement with HB Antwerp.Zara Boldt has quit as chief financial officer and John Armstrong has resigned as vice president of technical services, the company said in a statement. They will both leave in December.Their departures come as Lucara navigates choppy waters. Eira Thomas resigned in August as CEO, and the underground expansion at Karowe, in Botswana, is over-time and over-budget.Lucara walked away from an innovative 10-year sales agreement with HB Antwerp last week, citing "a material breach of financial commitments".Paul Conibear, chairman of Lucara's board, thanked Boldt and Armstrong for their hard work and dedication, and acknowledged their "meaningful contributions".