Amber is fossilized tree resin often used in jewelry.
Living trees produce resin as a protective substance that can seal wounds and deter insects or microbes. When resin becomes buried in sediment and remains under favorable conditions for millions of years, chemical changes remove volatile compounds and harden it into amber. The process is different from the fossilization of wood, which involves the replacement or preservation of plant tissues.
Amber ranges from pale yellow to orange, red, brown, and nearly black. Some pieces are transparent, while others contain bubbles, plant fragments, or insects trapped before the resin hardened. These inclusions can preserve remarkably detailed snapshots of ancient terrestrial ecosystems.
The Baltic region is famous for large amber deposits, and Baltic amber is associated with sediments formed during the Eocene. Amber is not a mineral because it is organic and lacks a crystal structure. Jet, another organic gem material, is a type of fossilized wood and is therefore distinct from amber.