amber - fossil amber from a tropical forest tree in Indonesian Borneo
Amber is fossilized tree resin, found world wide. Amber is common in Borneo, in Indonesian Borneo, Malyasian Borneo and in the Sultanate of Brunei. This amber is from Indonesian Borneo and is thought to be Miocene in age.
The source of this amber is a tree in the family Dipterocarpaceae, a group of lowland tropical rainforest trees with two-winged seeds. The name is derived from the Greek: di = two, pteron = wing, and karpos = fruit. Borneo amber comes primarily from deposits of Tertiary age and is, in some areas, associated with coal. The largest piece found, weighing 68 kilograms, was collected from the Merit-Pila coal mine in Maylasian Borneo (Sarawak).
During fossilization, tree resins lose volatiles and become polymerized, a process that begins when the resin is exposed to air and sunlight. Buried resins also mature, more rapidly when exposed to temperature and pressure. This amber fluoresces yellow under longwave ultraviolet.
When to call a fossil resin "amber" is unsettled. K.B. Anderson, in The nature and fate of natural resins in the geosphere-VII. A radiocarbon (14C) age scale for description of immature natural resins: an invitation to scientific debate: Org. Geochem. Vol. 25, No. 314, pp. 251-253, 1996, considered fossil resins older than 40 thousand years as a fossil and named an "amber."