Roedd cynhyrchu dur drwy ddefnyddio glo carreg lleol yn broses unigryw i Gymru - cafodd adeiladwaith to dur y Tŷ Gwyn ei wneud ym Mhontardawe ar ddiwedd y 19eg ganrif.
Unique to Wales was the manufacturing of steel using local anthracite coal - the steel roof structure of the White House was made in Pontardawe, south Wales in the late 19th century.