Amber has often been imitated by other resins like copal and kauri, as well as by celluloid and even glass.
Buried in this clay-marl are found large deposits of the fossil resin which becomes the kauri gum of commerce; and on the surface extensive forests are still a great though diminishing source of wealth.
Though much of the timber is of commercial value - notably the kauri, totara, puriri, rimu, matai and kahikatea - this has not saved the forests from wholesale, often reckless, destruction.
Kauri gum still holds its place as an export, over £500,000 worth being dug up annually.
The number of Istrians and Dalmatians who came from the Adriatic to dig for kauri gum led to the passing of restrictive laws.