Beryl
Beryl is Be3Al2Si6O18: hexagonal prisms to 18 m, hardness 7.5 to 8, density 2.63 to 2.97. Emerald, aquamarine and morganite are all its colour varieties.
Beryl is beryllium aluminium silicate, Be3Al2Si6O18: hexagonal prisms, hardness 7.5 to 8, density 2.63 to 2.97 rising with alkali content. Emerald, aquamarine and morganite are colour varieties of this one species, not separate minerals. It is 5.03% beryllium by mass, and the Handbook records crystals to 18 m and 180 t.
In short
- One species, several gem names. The September 2026 IMA-CNMNC Master List has a single row, Beryl, grandfathered. GIA calls emerald the bluish green to green variety of beryl, aquamarine a color variety of the mineral beryl, and morganite the pink to orange-pink variety, coloured by traces of manganese.
- Hardness 7.5 to 8 is uncommon in this site’s reference set. Of the 176 sheets in this site’s reference set, 3 print a hardness reaching 7.5: corundum 9, topaz 8 and uvite 7.5. Twelve reach 7. Beryl’s own sheet is not in the set.
- Worked composition: Be3Al2Si6O18 is 13.96% BeO, 18.97% Al2O3 and 67.07% SiO2 on standard atomic weights. That is the Handbook of Mineralogy ideal column to the hundredth, and 5.03% beryllium by mass. The Nuristan, Afghanistan, analysis carries 3.79% Cs2O and only 10.79% BeO.
- 18 m and 180 t. Against the 176 sheets, only microcline prints a larger crystal, to 50 m; gypsum’s 17 m is next (script search of each Crystal Data field for to N m, cm or mm).
- Beryl is on the association lines of 4 of the 176 sheets: lepidolite, orthoclase, schorl and topaz. Its own association line reads quartz, feldspar, muscovite, lepidolite, spodumene, amblygonite, tourmaline, topaz, cassiterite, columbite and tantalite.
| Name | What it is | Formula | Hardness | Density / SG | Refractive index | Optical class or birefringence |
|---|---|---|---|---|---|---|
| Beryl (Handbook) | Species | Be3Al2Si6O18 | 7.5 to 8 | 2.63 to 2.97; 2.7 average | ω 1.567 to 1.610, ε 1.565 to 1.599 | Uniaxial (−) |
| Emerald (GIA) | Bluish green to green beryl | Be3Al2Si6O18 | 7.5 to 8 | 2.72 | 1.577 to 1.583 | Birefringence 0.005 to 0.009 |
| Aquamarine (GIA) | Greenish blue beryl | Be3Al2Si6O18 | 7.5 to 8.0 | 2.72 | 1.577 to 1.583 | Birefringence 0.005 to 0.009 |
| Morganite (GIA) | Pink to orange-pink beryl | Be3Al2Si6O18 | 7.5 to 8 | 2.80 to 2.91 | 1.583 to 1.590 | Birefringence 0.007 to 0.008 |
| Topaz | Species | Al2SiO4(F,OH)2 | 8 | 3.49 to 3.57 | α 1.606 to 1.634, γ 1.616 to 1.644 | Biaxial (+) |
| Quartz | Species | SiO2 | 7 | 2.65 | ω 1.544, ε 1.553 | Uniaxial (+) |
Is emerald a beryl? Species and varieties
Emerald, aquamarine and morganite are names for colours of one species. The IMA list has one row, Beryl, Be3Al2(Si6O18), G, grandfathered, with the year printed as ? and the country as unknown. GIA’s gem descriptions give the varieties: emerald, the bluish green to green variety of beryl; aquamarine, greenish blue, a color variety of the mineral beryl; morganite, the pink to orange-pink variety, whose colour GIA attributes to traces of manganese. GIA adds that gem experts differ on how green a stone must be to be called emerald rather than green beryl.
The Handbook sheet uses none of the variety names. Its colour field covers them all in one line: colorless, white, pale blue to sky-blue, bluish green through green to greenish yellow or yellow, rose to peach, deep pink to raspberry-red; may be zoned. The only emerald on it is in the title of Sinkankas’s 1981 book, Emeralds and other beryls. On a collector’s label the species is beryl, and the variety name can follow it in brackets.
The densities differ by variety. GIA gives specific gravity 2.72 for emerald and for aquamarine, and 2.80 to 2.91 for morganite. The Handbook gives 2.63 to 2.97, increasing with alkali content. The emerald-and-dioptase question has its own page, is dioptase the same as emerald, which is not repeated here.
How hard is beryl, against 176 other minerals?
Method: the Hardness field of all 176 sheets in this site’s reference set was parsed by script, after pdftotext -layout, taking the upper value of each printed range. 165 sheets print a number. The other 11 print n.d., Soft or an approximate value, none of them above 4. Three reach 7.5: corundum (9), topaz (8) and uvite (7.5). Twelve reach 7, including quartz, schorl, cassiterite, epidote and vesuvianite. Beryl’s 7.5 to 8 puts it with the top three. Its sheet is not in the set and is not counted.
What that means in the hand: beryl scratches quartz (7), and topaz (8) scratches it or matches it. Against the aquamarine-coloured stones it is confused with, density is the better test. Topaz is 3.49 to 3.57, and quartz 2.65, which sits inside beryl’s 2.63 to 2.97. Optics separate all three: beryl uniaxial negative, quartz uniaxial positive, topaz biaxial positive. See how to test mineral hardness properly and how to measure specific gravity at home.
What is beryl made of? Beryllium by mass, worked
On standard atomic weights (Be 9.0122, Al 26.9815, Si 28.085, O 15.999), Be3Al2Si6O18 has a formula mass of 537.49. As oxides that is BeO 13.96%, Al2O3 18.97%, SiO2 67.07%, the sheet’s ideal column exactly. As elements it is 5.03% beryllium, 10.04% aluminium and 31.35% silicon.
The two analyses on the sheet sit either side of that. Mursinka, Russia, reads BeO 13.46%, 96.4% of the ideal, with 1.16% FeO. The Nuristan district, Afghanistan, analysis reads BeO 10.79%, 77.3% of the ideal, with Cs2O 3.79%, Li2O 1.30% and Na2O 1.23%. The sheet says density and refractive indices both increase with alkali content; its density range is 2.63 to 2.97.
How big do beryl crystals get?
The Handbook prints crystals prismatic to tabular, to 18 m and 180 t, with the prism {10-10}, the basal pinacoid {0001} and the second-order prism {11-20}. The indices were read from the rendered sheet, and each passes h+k+i=0. It adds radial, trapiche, columnar; granular to compact. It names giant crystals from the Malakialina district, Madagascar, but does not say which locality produced the 18 m figure, and neither do we.
Against the 176 sheets in the set, a script search of every Crystal Data field for to N m, cm or mm finds 151 sheets that print a size. The largest are microcline, to 50 m (perhaps the largest of any species, its sheet says), gypsum to 17 m, phlogopite to 10 m, calcite to 7 m and quartz to 6 m. Beryl’s 18 m would be second. The microcline sheet names the Devil’s Hole beryl mine, Fremont Co., Colorado, for large crystals; see microcline.
Where beryl is found
The Handbook records beryl in granites and granite pegmatites, rarely in nepheline syenites. It also occurs in mafic metamorphic rocks, in low- to high-temperature hydrothermal veins and in vugs in rhyolite. Its localities for fine specimens include the Mursinka-Alabashka area, Urals; Volhynia, Ukraine; Alto Ligonha, Mozambique; Mt. Bity, Madagascar; Jos, Nigeria; Sandawana, Zimbabwe; and, for exceptional green crystals, the Muzo and Chivor districts, Boyacá, Colombia. Also named are Teófilo Otoni, Governador Valadares and Itabira, Minas Gerais, Brazil; Swat, Skardu and Hunza, Pakistan; and the Panjshir Valley, Afghanistan. In the USA it names Pala, California; Hiddenite, North Carolina; fine red crystals in the Wah Wah Mountains, Utah; and Mt. Antero, Colorado. No British locality is on the sheet.
The company it keeps is the pegmatite suite on its association line. Among the sheets in the set it pairs with lepidolite, muscovite, cassiterite and orthoclase. The fluorcalciomicrolite sheet lists beryl among its associates; see microlite. The rest of the silicates are indexed at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.