| Beryl | |
|---|---|
 | |
| General | |
| Category | Cyclosilicate |
| Formula (repeating unit) | Be3Al2Si6O18 |
| IMA symbol | Brl[1] |
| Strunz classification | 9.CJ.05 |
| Crystal system | Hexagonal |
| Crystal class | Dihexagonal dipyramidal (6/mmm) H-M symbol: (6/m 2/m 2/m) |
| Space group | P6/mcc |
| Unit cell | a = 9.21 Å, c = 9.19 Å; Z = 2 |
| Identification | |
| Formula mass | 537.50 g/mol |
| Color | Green, blue, yellow, colorless, pink, and others |
| Crystal habit | Prismatic to tabular crystals; radial, columnar; granular to compact massive |
| Twinning | Rare |
| Cleavage | Imperfect on {0001} |
| Fracture | Conchoidal to irregular |
| Tenacity | Brittle |
| Mohs scale hardness | 7.5–8.0 |
| Luster | Vitreous to resinous |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.63–2.92 |
| Optical properties | Uniaxial (−) |
| Refractive index | nω = 1.564–1.595 nε = 1.568–1.602 |
| Birefringence | δ = 0.0040–0.0070 |
| Pleochroism | Weak to distinct |
| Ultraviolet fluorescence | None (some fracture-filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not). Morganite has weak violet fluorescence. |
| References | [2][3][4][5]: 112 |
Beryl (/ˈbɛrəl/ BERR-əl) is a mineral composed of beryllium aluminium silicate with the chemical formula Be3Al2Si6O18.[6] Well-known varieties of beryl include emerald and aquamarine. Naturally occurring hexagonal crystals of beryl can be up to several meters in size, but terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, pink, and red (the rarest). It is an ore source of beryllium.[7]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ "Beryl". mindat.org. Archived from the original on 26 October 2007.
- ^ "Beryl Mineral Data". webmineral.org. Archived from the original on 12 May 2008.
- ^ "Beryl" (PDF). Mineral Data Publishing. 2001. Archived (PDF) from the original on 28 November 2011.
- ^ Schumann, Walter (2009). Gemstones of the World. Sterling Publishing Co. ISBN 978-1-402-76829-3. Archived from the original on 20 November 2017. Retrieved 22 May 2018.
- ^ "Beryl". www.minerals.net. Retrieved 12 July 2018.
- ^ Klein, Cornelis; Dutrow, Barbara; Dana, James Dwight (2007). The Manual of Mineral Science (after James D. Dana) (23rd ed.). Hoboken, N.J.: J. Wiley. ISBN 978-0-471-72157-4. OCLC 76798190.