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.
In 1895 began a marked commercial revival, mainly due to the steady conversion of the colony's waste lands into pasture; the development of frozen meat and dairy exports; the continuous increase of the output of coal; the invention of gold-dredging; the revival and improvement of hemp manufacture; the exploiting of the deposits of kauri gum; the reduction in the rates of interest on mortgage money; a general rise in wages, obtained without strikes, and partially secured by law, which has increased the spending power of the working classes.
Certain resins are obtained in a fossilized condition, amber being the most notable instance of this class; African copal and the kauri gum of New Zealand are also procured in a semi-fossil condition.
The Kauri pine (Dammara australis) is a native of New Zealand.
The Anglican church of St Mary is built of Oamaru and bluestone, with a roof of kauri wood.
A characteristic feature of the genus Agathis (Dammara) the Kauri pine of New Zealand, is the deciduous habit of the branches; these become detached from the main trunk leaving a well-defined absciss-surface, which appears as a depressed circular scar on the stem.
Among the many valuable timber trees are the vesi (Afzelia bijuga); the dilo (Calophyllum Inophyllum), the oil from its seeds being much used in the islands, as in India, in the treatment of rheumatism; the dakua (Dammara Vitiensis), allied to the New Zealand kauri, and others.