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@article{2247301,
author = {Henry, Rhiana E. and Groat, Lee A. and Evans, R. James and Cempírek, Jan and Škoda, Radek},
article_number = {4},
doi = {http://dx.doi.org/10.3749/canmin.2100050},
keywords = {beryl; crystallography; water; sodium; mineralogy; crystal chemistry; emerald; aquamarine},
language = {eng},
issn = {0008-4476},
journal = {Canadian Mineralogist},
title = {Crystal-Chemical Observations and the Relation Between Sodium and H2O in Different Beryl Varieties},
url = {https://doi.org/10.3749/canmin.2100050},
volume = {60},
year = {2022}
}
TY - JOUR
ID - 2247301
AU - Henry, Rhiana E. - Groat, Lee A. - Evans, R. James - Cempírek, Jan - Škoda, Radek
PY - 2022
TI - Crystal-Chemical Observations and the Relation Between Sodium and H2O in Different Beryl Varieties
JF - Canadian Mineralogist
VL - 60
IS - 4
SP - 625-675
EP - 625-675
PB - Mineralogical Association of Canada
SN - 00084476
KW - beryl
KW - crystallography
KW - water
KW - sodium
KW - mineralogy
KW - crystal chemistry
KW - emerald
KW - aquamarine
UR - https://doi.org/10.3749/canmin.2100050
N2 - Beryl (Be3Al2Si6O18) is a well-known mineral, most famously in its vivid green form of emerald, but also as a range of other colors. Prominent varieties of beryl aside from emerald include aquamarine, red beryl, heliodor, goshenite, and morganite. There has not been a significant amount of research dedicated to comparing the crystal-chemical differences among the varieties of beryl except in determining chromophoric cations. While the H2O content within structural channels of emerald has been explored, and the H2O content of individual beryl specimens has been studied, there has not yet been a study comparing the H2O content systematically across beryl varieties. In this study we consider single-crystal X-ray diffraction data and electron probe microanalyses of 80 beryl specimens of six primary varieties, to compare and contrast their crystal chemistry. Beryl cation substitutions are dominantly coupled substitutions that require Na to enter a structural channel site. The results indicate that with increasing Na content beryl varieties diverge into two groups, characterized by substitutions at octahedral or tetrahedral sites, and that the dominant overall cation substitutions in each beryl variety tend to be different in more than just their chromophores. We find that the relation between Na and H2O content in beryl is consistent for beryl with significant Na content, but not among beryl with low Na content. Natural red beryl is found to be anhydrous, and heliodor has Na content too low to reliably determine H2O content from measured Na. We determined equations and recommendations to relate the Na and H2O content in emerald, aquamarine, goshenite, and morganite from a crystallographic perspective that is applicable to beryl chemistry measured by other means. This research will help guide future beryl studies in classifying beryl variety by chemistry and structure and allow the calculation of H2O content in a range of beryl varieties from easily measured Na content instead of requiring the use of expensive or destructive methods.
ER -
HENRY, Rhiana E., Lee A. GROAT, R. James EVANS, Jan CEMPÍREK and Radek ŠKODA. Crystal-Chemical Observations and the Relation Between Sodium and H2O in Different Beryl Varieties. \textit{Canadian Mineralogist}. Mineralogical Association of Canada, 2022, vol.~60, No~4, p.~625-675. ISSN~0008-4476. Available from: https://dx.doi.org/10.3749/canmin.2100050.
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