Beryllium · element 4
Light as magnesium, stiff as steel, and the element hiding inside every emerald
Key facts
Beryllium is a hard, grey metal that combines two properties engineers rarely get together: it is very light and very stiff. It resists bending better than steel while weighing about a quarter as much. It is also transparent to X-rays, an excellent conductor of heat, and hard to find. Beryllium is one of the rarer elements in the Earth's crust and is expensive to refine.
Its name comes from beryl, the mineral in which it was first found. Emerald and aquamarine are both beryl, coloured by traces of other elements. Beryllium is a strange mixture of the beautiful and the hazardous, because the same metal that sits in gemstones and space telescope mirrors is seriously toxic to breathe as dust.
Where it is found
Beryllium makes up only a few parts per million of the Earth's crust. It is concentrated in a small number of minerals, chiefly beryl, a beryllium aluminium silicate, and bertrandite, a hydrated silicate mined mainly in Utah. The United States produces most of the world's beryllium, with smaller amounts from China and Kazakhstan.
In the universe beryllium is scarce. Stars burn it as fast as they make it. Most of the beryllium in the cosmos is thought to form when cosmic rays smash heavier nuclei apart in interstellar space. A radioactive isotope, beryllium-10, is made in the atmosphere by cosmic rays and is used to date ice cores and study past solar activity.
How it was discovered
In 1798 the French chemist Louis Nicolas Vauquelin was asked by the mineralogist Rene Just Hauy to check whether beryl and emerald were chemically the same mineral. They were, and both contained an oxide nobody had seen before. Vauquelin noticed that its salts tasted sweet, and the new element was for a time called glucinium, from the Greek for sweet. Tasting unknown chemicals is a habit chemists have since abandoned, and in beryllium's case with good reason.
The metal itself was not isolated until 1828, when Friedrich Wohler in Germany and Antoine Bussy in France independently reduced beryllium chloride with potassium. The name beryllium eventually won out over glucinium and became the official name in the twentieth century.
What we use it for
Most beryllium is used in alloys. Adding a small percentage to copper gives a material that is springy, hard-wearing, does not spark when struck and conducts electricity well. Beryllium copper appears in electrical connectors, precision springs, aircraft bushings and non-sparking tools for oil rigs and mines.
Pure beryllium is chosen where weight and stiffness matter most. The James Webb Space Telescope's segmented mirror is made of gold-coated beryllium because it keeps its shape at extremely low temperatures. Beryllium windows let X-rays out of X-ray tubes while keeping air out. In nuclear engineering it reflects and moderates neutrons. Beryllium oxide is a ceramic that conducts heat like a metal but insulates against electricity, which makes it valuable in electronics.
Reading the numbers
Beryllium melts at about 1287 degrees Celsius and boils at about 2469 degrees, far higher than its neighbours lithium and magnesium. Its density of 1.85 grams per cubic centimetre is less than twice that of water and less than a quarter that of iron, yet it is one of the stiffest metals known. That combination is why it is used in components that must not flex.
The configuration [He] 2s2 shows two electrons in the outer shell, so beryllium forms Be2+ ions and sits in group 2. Its first two ionisation energies, 900 and 1757 kilojoules per mole, are high for a group 2 metal, and its electronegativity of 1.57 is unusually high too. The result is that beryllium's bonds have a good deal of covalent character and its chemistry resembles aluminium's more than magnesium's. Beryllium is the smallest atom in its group, which explains this unusual behaviour.
Safety and the environment
Beryllium is one of the most toxic elements to inhale. Fine dust or fumes from machining or grinding can cause berylliosis, a chronic scarring of the lungs that may appear years after exposure. Some people become sensitised to it after very small doses. Beryllium compounds are also classed as carcinogenic. Handling solid beryllium metal or a beryl gemstone is not a hazard; the danger arises when particles become airborne.
For this reason, workplaces that machine beryllium use strict extraction, protective equipment and health monitoring. In the environment, beryllium in soil and water is generally at very low levels and is not readily taken up by plants.
Did you know?
- Emerald and aquamarine are both the mineral beryl, a beryllium aluminium silicate. Traces of chromium make emerald green and traces of iron make aquamarine blue.
- James Chadwick discovered the neutron in 1932 by firing alpha particles at a beryllium target.
- The mirror of the James Webb Space Telescope is made from beryllium coated with a thin layer of gold.
- Beryllium is nearly transparent to X-rays, so thin beryllium foil is used as the window on X-ray tubes.
- Beryllium is the lightest element with only one stable isotope, beryllium-9.
- Beryllium copper tools do not spark when struck, so they are used where flammable gases could ignite.
More in the alkaline earth metals
These share a column with beryllium, so their outer electrons are arranged in a similar way and they tend to behave alike.
See all 6 alkaline earth metals on one page, or browse all 118 elements.
Compare Beryllium with another element
Each comparison has a side-by-side data table and a plain-English summary of the differences.
Frequently asked questions
Is beryllium dangerous?
As dust or fumes, yes. Breathing fine beryllium particles can cause a serious lung disease called berylliosis, and beryllium compounds are carcinogenic. Solid beryllium metal, beryllium copper alloys and beryl gemstones are safe to handle because nothing becomes airborne.
What is beryllium used for?
Mostly in beryllium copper alloys for springs, connectors and non-sparking tools. Pure beryllium is used for X-ray windows, aerospace structures, telescope mirrors and neutron reflectors in nuclear reactors.
Why is beryllium so expensive?
It is rare in the crust, mined in only a few places, and difficult to extract from its minerals. Processing must also be done under strict safety controls because of its toxicity, which adds to the cost.
Is there beryllium in emeralds?
Yes. Emerald is the mineral beryl, whose chemical formula contains beryllium, aluminium, silicon and oxygen. The green colour comes from a trace of chromium, and sometimes vanadium, replacing some of the aluminium.
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Written by Anthony. Updated September 2026. Numerical data from Periodic-Table-JSON (CC BY-SA), cross-checked against the Beryllium reference article. Spotted an error? Tell us.