Amber is a naturally occurring, hardened, translucent fossil resin that has been appreciated for its color and beauty since Neolithic times. It is primarily a yellowish-brown substance, though it can exhibit a range of colors from whitish to almost black, including rare shades of red, green, and blue. Often used in jewelry and ornamental objects.
From Tree Resin to Fossil
Amber originates as a sticky, viscous tree resin, not to be confused with watery tree sap. Trees produce resin as a defense mechanism, exuding it from specialized ducts to seal wounds, deter insects, and protect against fungal infections. This resin can flow down branches and trunks, forming blobs or sheets, sometimes dripping onto the forest floor.
Not all resin transforms into amber. For fossilization, the resin must possess specific chemical properties resistant to decay. Exposure to sunlight, rain, microorganisms, and extreme temperatures typically causes resin to disintegrate quickly. Only certain types of resin from ancient trees, primarily conifers, have the stability to become amber.
The Long Journey to Mineralization
The transformation of tree resin into amber is a complex geological and chemical process spanning millions of years. After exudation, the resin must be rapidly buried under sediment, such as sand or clay, to protect it from oxidation and decomposition. This burial creates an anaerobic, or oxygen-poor, environment necessary for preservation.
Over vast geological timescales, ranging from 2 to 100 million years, the buried resin is subjected to increasing pressure and moderate temperatures. These conditions initiate a chemical change called polymerization. During this process, smaller molecules within the resin link to form larger, more stable molecular chains, while volatile compounds evaporate or are expelled.
This hardening first turns the resin into copal, a semi-fossilized substance, sometimes called “young amber.” With continued heat and pressure, the copal further matures, driving off remaining volatile terpenes and completing the transformation into durable, inert true amber. The time required for “amberization” depends on the environmental conditions of its burial.
Global Deposits and Ancient Forests
Significant amber deposits are found worldwide, correlating to where ancient, resin-producing forests once thrived. These forests existed in warm, humid climates conducive to abundant resin production. The geological history of these regions, including sediment deposition and tectonic activity, was important for preserving the resin.
The Baltic Sea region is the most prominent source, providing over 90% of the world’s amber, known as Baltic amber or succinite. This amber formed from the resin of extinct coniferous trees that grew across northern Europe 35-55 million years ago during the Eocene epoch.
Another notable source is the Dominican Republic, where amber formed from the resin of an extinct leguminous tree, Hymenaea protera. This amber, often clearer and rich in inclusions, dates back 15-40 million years. Other deposits include Burmese amber (Burmite) from Myanmar, dating to approximately 99 million years ago, and Mexican amber, also from Hymenaea trees.