Barton, Mark D. Department of Earth and Space Sciences, University of California, Los Angeles, California.
Last reviewed:February 2021
Show previous versions
- Related Primary Literature
- Additional Reading
The most common beryllium mineral. Beryl, Al2[Be3Si6O18], crystallizes in the hexagonal system with space group P6/mcc. The crystal structure consists of six-membered rings of corner-sharing silicon-oxygen (SiO4) tetrahedra cross-linked by corner-sharing beryllium-oxygen (BeO4) tetrahedra to make a three-dimensional honeycomb structure; aluminum-oxygen (AlO6) octahedra lie between the Si6O18 rings. Cordierite, (Mg,Fe)2[Al4Si5O18], has a similar structure. Open channels parallel to the sixfold axis contain variable amounts of alkalies (up to 5–8 wt %), such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs), and water molecules (up to ∼2.5 wt %). Minor amounts of iron (Fe), chromium (Cr), manganese (Mn), and other metals substitute for aluminum, contributing to the various colors of natural beryl. Beryl has a vitreous luster and is typically white to bluish- or yellowish-green, but it can also be shades of yellow, blue, and pink (see illustration). Its hardness is 7.5–8 on Mohs scale; it has an imperfect basal cleavage and a specific gravity of 2.7–2.9 (increasing with alkali content). Weakly colored varieties can be confused with quartz or apatite. See also: Crystal structure; Hardness scales
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 10,000 highly qualified scientists and 46 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information