Is chrysoberyl a beryl?
Chrysoberyl is not a beryl: BeAl2O4, an oxide, against beryl’s Be3Al2(Si6O18). It has 1.41 times beryl’s BeO by mass, and a 20 g specimen reads 1.40 g heavier.
No. Chrysoberyl is not a beryl. It is beryllium aluminium oxide, BeAl2O4, orthorhombic, hardness 8.5; beryl is a silicate, Be3Al2(Si6O18), hexagonal, hardness 7.5 to 8. They are separate species on the September 2026 IMA list. The shared name is etymology, and chrysoberyl in fact carries more beryllium: 19.70% BeO against 13.96%.
In short
- Two species, two classes. The September 2026 IMA-CNMNC Master List lists chrysoberyl, BeAl2O4, grandfathered, 1789, Brazil, and beryl, Be3Al2(Si6O18), grandfathered, year printed as ?. One is an oxide with no silicon; the other a silicate built on a six-silicon group. Their species pages are chrysoberyl and beryl.
- The silicon test. If the formula has no silicon, it is not a beryl. A script over the IMA list finds 4 rows with beryl in the name: beryl, beryllite Be3(SiO4)(OH)2·H2O, beryllonite NaBe(PO4) and chrysoberyl BeAl2O4. Only two contain both beryllium and aluminium, and of those only beryl has silicon. A shared syllable is not a shared structure.
- More beryllium, not less. On standard atomic weights, chrysoberyl is 19.70% BeO and 7.10% beryllium by mass; beryl is 13.96% BeO and 5.03% beryllium. Chrysoberyl carries 1.41 times as much. The atom ratio runs the other way: one beryllium per two aluminium in chrysoberyl, three per two in beryl. The worked compositions of each species are on their own pages and agree with these.
- The 1.40 g gap. A 20.00 g piece reads 14.67 g in water as chrysoberyl (density 3.75) and 12.40 to 13.27 g as beryl (2.63 to 2.97), so the two cannot share a reading. Hardness also separates them, 8.5 against 7.5 to 8, and so does optics: chrysoberyl is biaxial with indices 1.746 to 1.756, beryl uniaxial with ω 1.567 to 1.610.
- They do meet. The chrysoberyl sheet lists beryl among its granite-pegmatite associates, and both sheets name Mursinka in the Urals and Teófilo Otoni in Minas Gerais. One specimen can carry both minerals; neither is a variety of the other.
| Criterion | Chrysoberyl | Beryl | Separates them? |
|---|---|---|---|
| IMA formula | BeAl2O4 | Be3Al2(Si6O18) | Yes |
| Silicon per formula unit | 0 | 6 | Yes: the silicon test |
| IMA status, year, country | G, 1789, Brazil | G, ?, unknown | — |
| Beryllium : aluminium atoms | 1 : 2 | 3 : 2 | Yes |
| BeO by mass (worked) | 19.70% | 13.96% | Yes: 1.41 times |
| Be by mass (worked) | 7.10% | 5.03% | Yes |
| Crystal system | Orthorhombic | Hexagonal | Yes |
| Hardness | 8.5 | 7.5 to 8 | Yes, by 0.5 at the closest |
| Density (measured) | 3.75 | 2.63 to 2.97 | Yes |
| 20.00 g piece in water | 14.67 g | 12.40 to 13.27 g | Yes: 1.40 g gap |
| Optical class | Biaxial (+) | Uniaxial (−) | Yes |
| Refractive indices | α 1.746, β 1.748, γ 1.756 | ω 1.567 to 1.610, ε 1.565 to 1.599 | Yes |
| Colour (sheet) | Greens, yellow, brownish to greenish black; raspberry-red under incandescent light when chromian | Colourless, blues, greens, yellow, rose to peach, pink to raspberry-red | No: both span greens and yellows |
| Named varieties | Alexandrite; cat’s-eye (chatoyant with oriented inclusions) | Emerald, aquamarine, morganite (GIA, as quoted on the beryl page) | — |
Is chrysoberyl a type of beryl? The criteria
Chrysoberyl is not a type of beryl: it is a separate species, an oxide, with its own row on the IMA list. The criteria, in order: formula, crystal system, and whether the name has its own IMA row. A variety name such as emerald has no row and shares its species’ formula; chrysoberyl has its own row, a different formula and a different crystal system. The September 2026 list gives chrysoberyl, BeAl2O4, grandfathered, 1789, Brazil, and beryl, Be3Al2(Si6O18), grandfathered, with the year printed as ? and the country as unknown.
The sheets agree. The Handbook chrysoberyl sheet gives BeAl2O4, orthorhombic, hardness 8.5, measured density 3.75, biaxial positive, indices α 1.746, β 1.748, γ 1.756. The Handbook beryl sheet gives Be3Al2Si6O18, hexagonal, hardness 7.5 to 8, density 2.63 to 2.97 increasing with alkali content, uniaxial negative, ω 1.567 to 1.610 and ε 1.565 to 1.599; its cited reference volume is Deer, Howie and Zussman’s on disilicates and ring silicates.
Where the name comes from. The chrysoberyl sheet derives it from the Greek for golden, in allusion to the mineral’s colour, and beryl. The beryl sheet gives beryl from the Greek beryllos, original significance unknown. Here the name records the colour, per the sheet, not the chemistry.
The silicon test: one element decides it
The silicon test: a mineral with no silicon in its formula is not a beryl, and chrysoberyl has none. Beryl’s formula on the IMA list brackets a group of six silicon and eighteen oxygen, (Si6O18). Chrysoberyl’s, BeAl2O4, has beryllium, aluminium and oxygen only.
Method. A script took every row of the September 2026 IMA list (pdftotext -layout) whose line contains beryl in any case. It finds 4: Beryl Be3Al2(Si6O18); Beryllite Be3(SiO4)(OH)2·H2O, 1954, Russia; Beryllonite NaBe(PO4), 1888, USA; and Chrysoberyl BeAl2O4. All 4 contain beryllium. Two contain aluminium: beryl and chrysoberyl. Of those two, only beryl contains silicon. Beryllite is a silicate without aluminium and beryllonite a phosphate; neither is a beryl either. The name is shared; the formula decides the species.
Who the test is wrong for. It answers the beryl question only, and says nothing about corundum or topaz, the gems chrysoberyl is more often weighed against; that comparison is the chrysoberyl page’s own two-bracket rule, linked rather than repeated. Alexandrite is chrysoberyl, not beryl; the variety question has its own page, is chrysoberyl the same as alexandrite.
Which has more beryllium, chrysoberyl or beryl? Worked
Chrysoberyl has more beryllium by mass than beryl: 7.10% against 5.03%, or 19.70% BeO against 13.96%. Worked on standard atomic weights (Be 9.0122, Al 26.9815, Si 28.085, O 15.999): BeAl2O4 has a formula mass of 126.97, of which one BeO is 25.01, so 19.70% BeO and 80.30% Al2O3. Be3Al2Si6O18 has a formula mass of 537.49, of which three BeO are 75.03, so 13.96% BeO, 18.97% Al2O3 and 67.07% SiO2. Both match the ideal columns printed on their sheets. The ratio is 19.70 / 13.96 = 1.41.
The atom count says the opposite, and both are true. Beryl has three beryllium per formula unit and chrysoberyl one, so per aluminium beryl has three times as much: 3 : 2 against 1 : 2. By mass chrysoberyl wins because beryl’s silicate part, 67.07% SiO2 by mass, carries no beryllium. The chrysoberyl sheet’s analysis from near Golden, Colorado, reads 19.15% BeO, 97.2% of the ideal, with 3.60% FeO.
In the hand. The weights do not overlap. A 20.00 g piece reads 14.67 g in water as chrysoberyl and 12.40 to 13.27 g as beryl, a gap of 1.40 g at the closest, 140 steps on a 0.01 g balance; the method is on how to measure specific gravity at home. Hardness 8.5 against 7.5 to 8 separates them too, but a scratch test on a cut stone damages it; see how to test mineral hardness properly.
Chrysoberyl or beryl on one specimen: who each name is wrong for
Chrysoberyl and beryl can share a specimen without either being a variety of the other. The chrysoberyl sheet places it in some granite pegmatites associated with high-grade mica schists, and lists its associates there as quartz, muscovite, albite, beryl, columbite, tourmaline, topaz, kyanite and staurolite. The beryl sheet’s association line does not name chrysoberyl. Both Distribution fields name Mursinka in the Ural Mountains and Teófilo Otoni in Minas Gerais; see Minas Gerais.
Who each name is wrong for. “Beryl” is wrong for any chrysoberyl, including alexandrite and cat’s-eye, which the chrysoberyl sheet records as chatoyant with oriented inclusions. “Chrysoberyl” is wrong for a yellow or green beryl, however golden; colour does not separate them, since both sheets span greens and yellows. Emerald, aquamarine and morganite are beryl, per GIA as quoted on the beryl page; the emerald comparison is on is dioptase the same as emerald and the aquamarine tests on how to tell if aquamarine is real.
What to write on a label. The species name from the IMA list, chrysoberyl or beryl, with any variety name after it. The classification questions are indexed at the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.