Chemistry:Prasiolite

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Prasiolite
General
CategoryTectosilicate minerals, quartz variety
Crystal systemTrigonal
Identification
ColorShades of green
Crystal habitHexagonal prisms
CleavageNone
FractureConchoidal[1]
TenacityBrittle[1]
Mohs scale hardness7 – lower in impure varieties[1]
DiaphaneityTransparent to nearly opaque
Specific gravity2.65
Refractive index1.544 to 1.553[2]
Birefringence0.009[3]
Ultraviolet fluorescenceNone

Prasiolite (also known as green quartz, green amethyst or vermarine) is a green variety of quartz, with its color typically coming from Fe2+ ions within the crystal structure.[1][4]

Natural prasiolite is exceedingly rare, having been first discovered in the early 19th century in Lower Silesia, Poland[5][6] with only a few other deposits known to exist. Natural prasiolite deposits include Płóczki Górne (Poland), Bahia (Brazil), Thunder Bay (Canada), and Farm Rooisand (Namibia).[6]

Nearly all commercially available prasiolite is artificial, either produced by heat-treating amethysts from certain locations[7] to 400-500 °C,[8] or irradiating yellow-tinged quartzes.[9] Most amethyst will turn yellow or orange when heated, producing heat-treated amethysts which are often marketed as citrine, but some amethyst will turn green when treated.[8] Significant prasiolite production began in the mid-1950s with the discovery that amethysts from the Montezuma mine in Minas Gerais, Brazil turned green when heat-treated.[10]

Most prasiolite sold is used in jewellery settings, where it can substitute for far more expensive gemstones, such as peridot, tsavorite, and emerald.[11] Prasiolite used for jewelry comes from two main sources: heat-treated amethyst from the Montezuma mine, and irradiated yellow-tinged quartz from various locations throughout Brazil.[4]

Green quartz is sometimes incorrectly called green amethyst,[12] which is not an acceptable name for the material according to Federal Trade Commission Guidelines.[13] Other names for green quartz include vermarine and lime citrine.[14]

The word prasiolite literally means "leek-green stone" and is derived from Ancient Greek πράσον prason meaning "leek" and λίθος lithos meaning "stone".[15][16] The stone was given its name due to its green-colored appearance.

Natural prasiolite is a very light, translucent green. Darker green quartz is generally the result of artificial treatment,[17] with lighter-colored prasiolite often irradiated with gamma rays as an attempt to obtain deeper colors.[18]

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 "Prasiolite gemstone information". http://www.gemdat.org/gem-40112.html. 
  2. ↑ Lazarelli. Blue Chart Gem Identification. p. 7. http://www.gembluechart.com. 
  3. ↑ "PRASIOLITE the green variety of quartz (aka Green Amethyst)". http://www.galleries.com/Prasiolite. 
  4. ↑ 4.0 4.1 Praszkier, Tomasz; Kenis, Piotr; Komza, Piotr. "Prasiolite from Sokołowiec area, Kaczawskie Mountains, Lower Silesia, Poland". https://www.spiriferminerals.com/index.php?static=163. 
  5. ↑ Czaja, Maria; Kądziołka-Gaweł, Mariola; Konefał, Adam; Sitko, Rafał; Teper, Ewa; Mazurak, Zbigniew; Sachanbiński, Michał (2017). "The Mössbauer spectra of prasiolite and amethyst crystals from Poland". Physics and Chemistry of Minerals 44: 1. doi:10.1007/s00269-016-0864-z. ISSN 1432-2021. https://link.springer.com/article/10.1007/s00269-016-0864-z. 
  6. ↑ 6.0 6.1 Platonov, Alexej N.; Szuszkiewicz, Adam (2015). "Green to blue-green quartz from Rakowice Wielkie (Sudetes, south-western Poland) – a re-examination of prasiolite-related colour varieties of quartz". Mineralogia 46 (1/2): 19–20. doi:10.1515/mipo-2016-0004. https://sciendo.com/es/article/10.1515/mipo-2016-0004. 
  7. ↑ Akhavan, Amir C. (2011). "Prasiolite". http://www.quartzpage.de/prasiolite.html. 
  8. ↑ 8.0 8.1 Henn, Ulrich; Schultz-Güttler, Rainer (2012). "Review of some current coloured quartz varieties". The Journal of Gemmology 33 (1-4): 34. doi:10.15506/JoG.2012.33.1.29. ISSN 1355-4565. https://gem-a.com/wp-content/uploads/2023/11/JoG2012_33_1-4.pdf. 
  9. ↑ "Prasiolite". https://www.edelsteine.at/en/glossaries/lexicon/prasiolite/. 
  10. ↑ Fryer, C. W. (1996). "QUARTZ, Single-Crystal Green". Gems & Gemology (Gemological Institute of America) 32 (3): 210–211. ISSN 0016-626X. https://www.gia.edu/doc/FA96.pdf. 
  11. ↑ Sedawie, Ross (2025). "Prasiolite Gemstone: Properties, Meanings, Value & More". https://www.gemrockauctions.com/learn/a-z-of-gemstones/prasiolite?srsltid=AfmBOopypjPmKvchAQ7CmKNtZmQaMTsc4yEmURhInHKV74_dJStkd6DZ. 
  12. ↑ "Green Amethyst". GemSelect. http://www.gemselect.com/other-info/green-amethyst.php. 
  13. ↑ 16 C.F.R. 23.26b
  14. ↑ "Green Quartz Meaning and Properties". n.d.. https://www.firemountaingems.com/resources/encyclobeadia/gem-notes/l55b. 
  15. ↑ Bailey, Dorothy; Bailey, Kenneth C. (1929). An Etymological Dictionary of Chemistry and Mineralogy. E. Arnold & Company. p. 222. https://books.google.com/books?id=bXdIAAAAMAAJ&pg=PA222. 
  16. ↑ "Prasiolite". https://www.langantiques.com/university/prasiolite-2/?srsltid=AfmBOore3mRfBLgQOWxRxvXKwtKeWkzvayevcz3wWfjS_imOLkVx7Ba6. 
  17. ↑ Gems and Gemstones: Timeless Natural Beauty of the Mineral World By Lance Grande, Allison Augustyn, p.91
  18. ↑ Nunes, Eduardo H.M.; Lameiras, Fernando S.; Houmard, Manuel; Vasconcelos, Wander L. (2013). "Spectroscopic study of natural quartz samples". Radiation Physics and Chemistry 90: 80. doi:10.1016/j.radphyschem.2013.05.003. ISSN 1879-0895. https://www.sciencedirect.com/science/article/pii/S0969806X13002697. 



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