Articles of stone or of other mineral substances (including carbon fibers, articles of carbon fibers and articles of peat), not elsewhere specified or included:
Containing by weight more than 70 percent magnesia, expressed as MgO, with carbon content ranging from trace amounts to less than 30 percent, and chemically bonded by resin or pitch
Containing by weight more than 70 percent magnesia, expressed as MgO, with carbon content ranging from trace amounts to less than 30 percent, and chemically bonded by resin or pitch