Amber

Amber is fossil resin. Not fossilised in the ordinary sense — nothing has been replaced by mineral — but chemically transformed in place: the volatile terpenes have gone, the remaining molecules have cross-linked into a polymer network, and what is left is an organic glass that no longer dissolves in the solvents that dissolve fresh resin.

That process needs time on a geological scale. Baltic amber, which is most of the world's supply, is around forty to fifty million years old. Dominican amber is fifteen to twenty. Burmese amber is Cretaceous, at roughly ninety-nine million, which puts its inclusions in the same world as the dinosaurs.

It is not a mineral, and no amount of common usage makes it one. It is organic, it has no crystal structure, and its composition varies continuously rather than sitting at a formula. It is treated here as a natural material used as a gemstone, which is what it actually is.

Two things are happening over those millions of years, and both are irreversible.

The volatile fraction leaves. Fresh resin is a third turpentine; amber has essentially none, and losing it is why amber is hard where resin is tacky, and why amber shrinks and crazes as it ages even after burial.

The rest polymerises. The terpene molecules that remain contain double bonds, and over geological time those bonds open and link neighbouring molecules into a three-dimensional network. Copal — resin part-way through the same journey — will still dissolve in alcohol and soften under a hot point. Amber will not, because the network has closed.

The preservation of inclusions follows from the same chemistry. An insect trapped in fresh resin is dehydrated by it, sterilised by its antimicrobial terpenes, and then sealed inside an oxygen-impermeable solid. What survives is usually the cuticle rather than the tissue — the widely repeated idea that amber preserves usable DNA has not held up, and attempts to recover it have failed repeatedly.

Amber has more convincing fakes than almost any other ornamental material, and four tests between them settle nearly every case.

Salt water. Amber floats in saturated brine and sinks in fresh water. Glass, most plastics and stone sink in both. This is the one test that costs nothing and rules out most of the field.

A hot point. Touched with a heated needle in an inconspicuous place, amber smells of pine and chars. Plastic smells of plastic and melts smoothly. Copal softens at a much lower temperature and goes sticky rather than charring.

Acetone. A drop on copal leaves it tacky within a minute. Amber is unaffected.

Ultraviolet. Amber fluoresces a pale blue, more strongly in Dominican material than Baltic. Most plastics do not.

The expensive mistake is not glass or plastic — it is copal, which is genuine tree resin only a few thousand to a few hundred thousand years old, and is what a spectacular insect in cheap 'amber' almost always turns out to be sitting in. Pressed amber, made by heating and compacting small fragments under pressure, is a further category: real amber, not a single piece, and detectable by the flow lines and the disc-shaped stress bubbles left in it.

The Greek for amber was ēlektron. Thales is said to have noticed around 600 BC that rubbing it attracts light objects, and when William Gilbert came to name that class of effect in 1600 he coined electricus from the Greek word — so 'electricity', 'electron' and 'electrode' all descend from the name of a fossil tree resin.

The English word 'amber' arrived by a different and stranger route: Arabic ʿanbar meant ambergris, the waxy secretion from a sperm whale's gut used in perfumery, and European languages transferred the name to the resin, which is not related to it in any way. The two were distinguished in medieval Latin as ambra grisea and ambra citrina, grey amber and yellow amber, and only the second kept the plain name.

Amber was traded across Europe before anyone worked metal. The Amber Road ran from the Baltic coast to the Adriatic and Mediterranean, and Baltic amber turns up in Mycenaean graves and in Tutankhamun's tomb — one of the earliest long-distance trades in any material, in a substance with no practical use whatever.

The Teutonic Order held a monopoly on Baltic collection in the thirteenth century and enforced it with the death penalty for unauthorised gathering, which is a striking amount of state violence in defence of an ornament.

The Amber Room, panelled entirely in amber mosaic and installed at the Catherine Palace near St Petersburg, was looted by German forces in 1941 and has never been found. The reconstruction completed in 2003 took twenty-four years.

The Baltic material is dredged and pit-mined, and the open-pit operation at Yantarny in Kaliningrad — which produces the large majority of world supply — is a substantial excavation with the water-table and spoil consequences of any pit of its size.

Burmese amber is a different problem entirely. Almost all of it comes from Kachin State in northern Myanmar, an area of active armed conflict, and the trade has been credibly documented as funding parties to that conflict. Because the same deposits produce scientifically extraordinary Cretaceous fossils, palaeontology has had to confront directly whether describing a specimen creates demand for more of them; several journals and the Society of Vertebrate Paleontology have restricted publication of Burmese amber material acquired after 2017 for that reason.

That is a rare and honest case of a research community accepting that its own interest is part of a market it does not like.