Beryl

minerals

tourmaline

beryllium

topaz

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Formula: Be₃Al₂Si₆O₁₈
Cyclosilicate (ring silicate), beryllium-bearing mineral

Varieties

Pure beryl is colourless, but it occurs in many different colours due to impurities. Together, divalent and trivalent iron, Fe²⁺ and Fe³⁺ generate the common sea-green color of beryl (R&M 90.2.140).

The blue-green colour of aquamarine is caused by trivalent iron Fe³⁺ (R&M 90.2.140).
The vivid green of emerald is caused by chromium Cr³⁺ and vanadium V³⁺ (R&M 90.2.140).
Goshenite is the colourless, gemmy variety of beryl.
The golden yellow colour of heliodor is caused by divalent iron Fe²⁺ being oxidised to trivalent Fe³⁺ by natural radiation (R&M 90.2.140).
The pink of morganite is caused by small amounts of divalent manganese Mn²⁺, and oxidation to Mn³⁺ causes the deep red of red beryl (R&M 90.2.140).
Red beryl is a gooseberry-red variety of beryl

Properties

Specific gravity: 2.63 to 2.92
Hardness: 7½ to 8
Streak: White
Solubility: Insoluble in hydrochloric, sulphuric and nitric acid
Common impurities: Fe,Mn,Mg,Ca,Cr,Na,Li,Cs,O,H,OH,H₂O,K,Rb
Environments:

Plutonic igneous environments
Pegmatites (typical)
Metamorphic environments

Beryl, although containing the rare element beryllium, Be, is rather common and widely distributed. It usually occurs in granitic rocks, or in pegmatites. All of the coloured varieties of beryl except the dark red hue are found in or in association with pegmatites. It is also found in mica schist of regional metamorphic rocks.

In pegmatites, associations include quartz, microcline, albite, muscovite, biotite, members of the columbite-tantalite series, cookeite, tourmaline, lepidolite, topaz and spessartine.
In medium-temperature metamorphic deposits beryl is associated with topaz, cassiterite and ferberite-hübnerite.
in Alpine and hydrothermal veins it is found with quartz and feldspar.

Red beryl is found in topaz rhyolites with topaz, high-temperature quartz and bixbyite-(Mn) (Extra Lapis 7.9).

Beryl crystallises in the hexagonal crystal system, point group 6/m 2/m 2/m, and crystals are usually simple prismatic, with forms {1010} and {0001} only. Rob Lavinsky, iRocks.com photo.

Localities

At the Kunar Valley, Nuristan, Afghanistan, beryl variety morganite occurs with spodumene variety kunzite, quartz, lepidolite and albite (R&M 90.2.139).
Morganite from Kunar - Image

At Tom's quarry, South Australia, beryl occurs intergrown with childrenite, variscite and strontium and iron bearing crandallite (AJM 17.1.28).

At Espírito Santo, Brazil, aquamarine beryl is common in all three fields of the pegmatite district. Alluvial specimens, rounded by transport and commonly deep blue, are typical of the Pancas Field; prismatic crystals of aquamarine and heliodor to more than 10 cm, in addition to crystals of green beryl, are also found in this area. Greenish beryls are common in the Mimoso do Sul Field in the south of the district. The most spectacular specimens of aquamarine are found at the Concordia Farm, Mimoso do Sul Field, where two unusual types of aquamarine crystal clusters occur. In the first type, thick, subhedral crystals of aquamarine form large, complex groups to 50 cm wide. The other type consists of distinctive aquamarines from a pocket discovered in 1990. The crystals are pale blue to pale green, gemmy, slightly etched, tapered prisms up to 8 cm in length, which come to a pencil-like point. Most specimens consist of loose jumbled clusters of thumbnail to miniature size, or scattered crystals on microcline - quartz matrix. Another aquamarine habit, found in the 1960s or early 1970s, consists of hexagonal prismatic crystals capped by a hexagonal bipyramid coming nearly to a point where the faces meet. The peculiar thing about these crystals is that they are heavily riddled by gaseous inclusions like bubbles in carbonated water. Because of the internal stresses posed by these inclusions, crystals are quite temperature-sensitive and have been known to burst from too much heat or even exposure to sunlight in a display case. An excellent aquamarine crystal has been reported from the Colatina area in the Santa Teresa Field; it weighed 25.2 kg, and was recovered from alluvium in the Vila das Penhas area.
Stream-rounded gemmological samples of heliodor have been collected, together with aquamarine and chrysoberyl, in an alluvial deposit at the Itajobi Farm, north of the town of Pancas. Heliodor also occurs as prismatic crystals in the Santa Teresa Field (Minrec 54.708-716).
Aquamarine from Espírito Santo - Image

At the Sapo mine, Ferruginha, Conselheiro Pena, Minas Gerais, Brazil, beryl occurs in pegmatite associated with quartz, albite and microcline (Min Rec 40.4.288-289).
Aquamarine from the Sapo Mine - Image

At the Pederneira claim, São José da Safira, Doce Valley, Minas Gerais, Brazil, beryl variety morganite has been found with elbaite (R&M 90.2.139).
Morganite from Pederneira - Image

At the Urucum mine, Minas Gerais, Brazil, beryl variety morganite has been found with schorl on albite (R&M 90.2.139).
Morganite from the Urucum Mine - Image

At Airy Creek, British Columbia, Canada, aquamarine occurs in a granitic pegmatite dyke that cuts high-grade metamorphic gneiss (R&M 85.1.30).

At the Tanco Mine, Bernic Lake, Lac-du-Bonnet area, Manitoba, Canada, a rare miarolitic crystal of cesium-rich, colourless beryl variety goshenite has been found (R&M 90.2.139).
The assemblages of minerals in the pegmatite were deposited in succession from petalite + quartz to spodumene + quartz to eucryptite + quartz (R&M 92.2.153).
Beryl from the Tanco Mine - Image

At Lened, Tungsten, Northwest Territories, Canada, emerald occurs in a series of vuggy quartz/carbonate veins within a calc-silicate skarn. The colour is probably due to traces of vanadium (R&M 85.1.28-29).
Emerald from Lened - Image

At the Little Nahanni Pegmatite Group, Tungsten, Northwest Territories, Canada, goshenite occurs within a series of lithium-bearing pegmatites.

At Mountain River, Mackenzie Mountains, Northwest Territories, Canada, emerald occurs in quartz-plagioclase-carbonate veins hosted in shale, siltstone and sandstone. The colour is due to chromium Cr and vanadium V (R&M 84.4.366-367).

At Port Joli, Nova Scotia, Canada, beryl occurs embedded in pegmatite within a biotite granite (R&M 85.1.31).

The Taylor pegmatite, Ontario, Canada, intrudes altered ultramafic rocks, which are the likely source of chromium which causes the green colour of the emerald which is found there (R&M 85.1.28 ).

At Devil's Peak, Sai Kung District, New Territories, Hong Kong, China, the mineralisation occurred in quartz veins in the contact zone between a granite intrusion and acid volcanic rocks. The mine is now closed, and inaccessible for collecting. Beryl was common and abundant in quartz veins (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)
Beryl from Devil's Peak - Image

The Lin Fa Shan deposit, Tsuen Wan District, New Territories, Hong Kong, China, is located in a remote area of the Tai Mo Shan Country Park, on a steep west facing slope of Lin Fa Shan, just above the abandoned village of Sheung Tong. The surrounding hillsides are covered with shallow excavations, representing past searches for wolframite, the natural ore of tungsten. The abandoned workings are extremely dangerous with unsupported tunnels, open shafts and no maintenance since their closures in 1957; the workings should not be entered (http://industrialhistoryhk.org/lin-shan).
Specimens of beryl and quartz bearing vein material in granite have been collected from the dumps, and beryl was sometimes found associated with muscovite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council).

At Pingwu County, Sichuan, China, beryl is associated with tin and tungsten minerals.
Beryl from Pingwu - Image

At Wenshan, Yunnan, China, beryl ocurs as isolated prismatic emerald crystals, up to several cm long, on a quartz matrix (AESS).
Emerald from Wenshan, Fabre Minerals specimen and Image

At Erongo, Namibia, schorl pseudomorphs after beryl have been found (KL p220).
Aquamarine from Erongo - Image

At the Shigar valley, Shigar district, Gilgit-Baltistan, Pakistan, beryl variety aquamarine has been found with inclusions and a surface druse of black tourmaline (R&M 90.2.139).
Aquamarine from the Shigar Valley - Image

At Dassu, Braldu Valley, Skardu District, Gilgit-Baltistan, Pakistan, beryl variety aquamarine occurs with spessartine, muscovite and feldspar (R&M 90.2.139).
Aquamarine from Dassu - Image

The Biangsapi Gon mine, Nyet Bruk, Nyet, Braldu Valley, Shigar District, Gilgit-Baltistan, Pakistan, was the source of a spectacular almost 200 kg specimen of gem-quality aquamarine crystals on matrix, known as the "King of Kashmir". It was extracted in 2019 in difficult and dangerous conditions from the mine high in precipitous mountains.
King of Kashmir - Images
(MinRec 51.755-778).

At the Teston village area, Braldu Valley, Skardu District, Gilgit-Baltistan, Pakistan, beryl occurs with albite and muscovite (R&M 94.5.438).

At the Haramosh mountains, Gilgit-Baltistan, Pakistan, beryl variety aquamarine occurs with spessartine on albite and muscovite (R&M 90.2.139).
Aquamarine from the Haramosh Mountains - Image

At Volodarsk-Volynskii, Zhytomyr Oblast, Ukraine, beryl variety heliodor has been found (R&M 90.2.139).
Heliodor from Khoroshiv Raion (Volodarsk-Volynskii) - Image

In the Sierrita Mountains, Pima County, Arizona, USA, aquamarine occurs in pegmatites embedded in white quartz enclosed by feldspar, with quartz and mica or in contact with biotite (R&M 88.3.222-230).
Beryl from the Sierrita Mountains - Image

At Yucca Valley, California, USA, aquamarine occurs in pockets in pegmatite associated with cleavelandite and smoky quartz (R&M 87.6.502-508).
Aquamarine from the Yucca Valley - Image

At the Emmons pegmatite, Greenwood, Oxford county, Maine, USA, beryl is common in the core. Associated minerals include pollucite, spodumene and amblygonite-montebrasite. In the intermediate zone most beryl has been replaced by beryllonite, bertrandite, fluorapatite, albite, hydroxylherderite and moraesite. The Emmons pegmatite is an example of a highly evolved boron-lithium-cesium-tantalum enriched pegmatite (R&M 94.6.505).
Aquamarine from the Emmons Quarry - Image

At Stoneham, Oxford county, Maine, USA, beryl occurs mostly in solid pegmatites, and only rarely in pockets. When it is in quartz it is aquamarine, but the beryl occurring in feldspar is common beryl (R&M 91.1.28-33).
Beryl from Stoneham - Image

The Consolidated Quarries at Sagadahoc County, Maine, USA, are in a simple granitic pegmatite, enriched in lithium in some zones. These have cavities which contain albite, muscovite and beryl, together with other minerals. The paragenesis for the beryl alteration is
beryl → beryllonite → moraesite → hydroxylherderite → fluorapatite → greifensteinite.
Late-stage low-temperature aqueous fluids likely caused partial dissolution of primary beryl resulting in the formation of hydroxylherderite and other secondary beryllium phosphates (R&M 90.3.275).
Beryl from Sagadahoc County - Image

In New Hampshire, USA, beryl is widespread in LCT pegmatites, but rarely found in NYF pegmatites (R&M 97.3.213-218).

Bald Mountain, Ossipee, Carroll County, New Hampshire, USA is one of the few New Hampshire localities where beryl is found in NYF pegmatites, rather than the more usual occurrences in LCT pegmatites. The blue to colourless crystals are typically less than 3cm in length, but crystals up to 9 cm occur occasionally. Some have inclusions of albite (R&M 97.3.213-218).
Beryl from Bald Mountain - Image

South Percy Peak locality, Stratford, Coos County, New Hampshire, USA is one of the few New Hampshire localities where beryl is found in NYF pegmatites, rather than the more usual occurrences in LCT pegmatites. The crystals are blue, up to a few cm in length, and occur in cavities (R&M 97.3.213-218).

At the Palermo No. 1 Mine, Groton, Grafton County, New Hampshire, USA, beryl crystals up to 3 metres long are found in the core zone, in a wide range of colours including white, blue, blue-green and golden. The golden colour is due to natural radiation, and golden beryl is generally found near uraninite and other radioactive species (R&M 97.3.213-218).
Beryl from the Palermo No. 1 Mine - Image

At the Keyes Mica Quarries, Orange, Grafton County, New Hampshire, USA, the pegmatites are beryl-type rare-element (RE) pegmatites.
The Number 1 mine exposed a pegmatite that shows the most complex zonation and diverse mineralogy of any of the Keyes pegmatites. Six zones are distinguished, as follows, proceeding inward from the margins of the pegmatite:
(1) quartz-muscovite-plagioclase border zone, 2.5 to 30.5 cm thick
(2) plagioclase-quartz-muscovite wall zone, 0.3 to 2.4 metres thick
(3) plagioclase-quartz-perthite-biotite outer intermediate zone, 0.3 to 5.2 metres thick, with lesser muscovite
(4) quartz-plagioclase-muscovite middle intermediate zone, 15.2 to 61.0 cm thick
(5) perthite-quartz inner intermediate zone, 0.9 to 4.6 meters thick
(6) quartz core, 1.5 to 3.0 metres across
The inner and outer intermediate zones contained perthite crystals up to 1.2 meters in size that were altered to vuggy albite-muscovite with fluorapatite crystals. This unit presumably was the source of the albite, muscovite, fluorapatite, quartz and other crystallised minerals found in pieces of vuggy albite rock on the dumps next to the mine.
The middle intermediate zone produced sheet mica with accessory minerals including tourmaline, graftonite, triphylite, vivianite, pyrite, pyrrhotite, and beryl crystals to 30.5 cm long and 12.7 cm across.
Beryl occurs chiefly at the Keyes Nos. 1 and 2 mines as crystals up to 30.5 cm long, embedded at the margins of quartz pods in a pillar at the No. 2 mine. The colours of Keyes beryl include pale green to olive-green, golden and aquamarine. Beryl specimens are also known from the No. 4 mine. Nearly all the beryl crystals were embedded in the pegmatite matrix. Gem-quality aquamarine and golden beryl were occasionally found at the Keyes mines (R&M 97.4.311-312).
Beryl from the Keyes Mica Quarries - Image

At the McGinnis Mine, Wentworth, Grafton County, New Hampshire, USA, beryl occurs as unusual 18-sided prismatic crystals, in colours ranging from straw-yellow to fine blue (R&M 97.3.213-218).
Aquamarine from the McGinnis Mine - Image

At the Beryl Mountain Quarry, South Acworth, Sullivan County, New Hampshire, USA, bluish green crystals of beryl up to 122 cm long have been found in the pegmatite, together with large rough crystals of feldspar, and mica in large plates, up to 1 square metre in area (R&M 97.3.213-218).
Beryl from the Beryl Mountain Quarry - Image

In New York City, USA, beryl crystals are found in pegmatites that cut schist and gneiss, and also frozen in a smoky quartz matrix.
Beryl from New York City - Image

At the Lost Hope mine, Miami, Karoi district, Mashonaland West, Zimbabwe, euclase pseudomorphs after beryl have been found (KL p220).

Alteration

At high temperature and pressure beryl commonly alters to different secondary minerals, depending on the pH.
At pH 2 to 3 (strongly acid) quartz is the dominant alteration product.
At pH 4 to 5 bertrandite, euclase or phenakite are formed.
Near the neutral pH of 7 bertrandite or bavenite are produced.
At pH of 8 to 9 (alkaline) bavenite, milarite or bityite are produced.
At pH 10 to 11 (strongly alkaline) epididymite or eudidymite are produced.
At high temperature and pressure beryl becomes unstable and breaks down into chrysoberyl, phenakite and quartz (Extra Lapis 7.9-10).

bertrandite, euclase and quartz to beryl and H₂O
Be₄Si₂O₇(OH)₂ + 8BeAlSiO₄(OH) + 14SiO₂ ⇌ 4Be₃Al₂Si₆O₁₈ + 5H₂O
Increasing temperature favours the forward reaction (AM 63.664-676).

bertrandite and kaolinite to euclase, beryl and H₂O
4Be₄Si₂O₇(OH)₂ + 7Al₂Si₂O₅(OH)₄ ⇌ 10BeAlSiO₄(OH) + 2Be₃Al₂Si₆O₁₈ + 13H₂O
Increasing temperature favours the forward reaction (AM 63.664-676).

bertrandite, kaolinite and quartz to beryl and H₂O
3Be₄Si₂O₇(OH)₂ + 4Al₂Si₂O₅(OH)₄ + 10SiO₂ ⇌ 4Be₃Al₂Si₆O₁₈ + 11H₂O
Increasing temperature favours the forward reaction (AM 63.664-676).

beryl to chrysoberyl, phenakite and silica (dry)
Be₃Al₂Si₆O₁₈ to BeAl₂O₄ + Be₂(SiO₄) + 5SiO₂ (dry)
Increasing temperature and pressure favours the forward reaction. At a pressure of 4 kbar the equilibrium temperatute is 1300 deg C (AM 71.277-300).

beryl and aluminium silicate to chrysoberyl and silica (water saturated)
Be₃Al₂Si₆O₁₈Be + 2Ky to 3BeAl₂O₄ + 8SiO₂ (water saturated)
At high pressure, above 8 kbar, the aluminium silicate phase is kyanite. Increasing temperature and decreasing pressure favours the forward reaction. At a pressure of 16 kbar the equilibrium temperature is about 850^oC (AM 71.277-300).

euclase to beryl, chrysoberyl, phenakite and H₂O
20BeAlSiO₄(OH) to 3Be₃Al₂Si₆O₁₈ + 7BeAl₂O₄ + 2Be₂(SiO₄) + 10H₂O
Increasing temperature and decreasing pressure favours the forward reaction. At a pressure of 6 kbar the equilibrium temperature is about 500^oC, in the absence of impurities which might be incorporated in the beryl (AM 71.277-300).

euclase to phenakite, chrysoberyl, beryl and H₂O
20BeAlSiO₄(OH) ⇌ 2Be₂(SiO₄) + 7BeAl₂O₄ + 3Be₃Al₂Si₆O₁₈ + 10H₂O
Increasing temperature favours the forward reaction (AM 63.664-676).

euclase and silica to beryl, chrysoberyl and H₂O
4BeAlSiO₄(OH) + 2SiO₂ to Be₃Al₂Si₆O₁₈ + BeAl₂O₄ + 2H₂O
Increasing temperature and decreasing pressure favours the forward reaction. At a pressure of 8 kbar the equilibrium temperature is about 500^oC, in the absnece of impurities which might be incorporated in the beryl (AM 71.277-300).

euclase and quartz to beryl, kaolinite and H₂O
6BeAlSiO₄(OH) + 8SiO₂ ⇌ 2Be₃Al₂Si₆O₁₈ + Al₂Si₂O₅(OH)₄ + H₂O
Increasing temperature favours the forward reaction (AM 63.664-676).

euclase and quartz to chrysoberyl, beryl and H₂O
4BeAlSiO₄(OH) + 2SiO₂ ⇌ BeAl₂O₄ + Be₃Al₂Si₆O₁₈ + 2H₂O
Increasing temperature favours the forward reaction (AM 63.664-676).

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