BeAl₂O₄

These samples of chrysoberyl are displayed in the Smithsonian Museum of Natural History. Chrysoberyl is an oxide mineral of beryllium with the composition BeAl₂O₄. The sample at left is about 10 cm across and is from Black Mountain, Rumford, Maine. This sample is described as chrysoberyl with quartz and schorl. A gem-quality variety of chrysoberyl is called Alexandrite.

These three chrysoberyl gems are from Minas Gerais, Brazil. They measure 46.3, 13.8 and 114.3 carats.

This gem measures 120.5 carats and is from Sri Lanka.

This large twinned crystal of chrysoberyl is about 20cm across and is from Espirito Santo, Brazil.

These chrysoberyl crystals are from Colatina, Espirito Santo, Brazil and are about 10 cm across. Each of them consists of three individual crystals that grew together at 60 degree angles, creating a snowflake effect. The angle is determined by the molecular geometry of chrysoberyl.

This is another example of cyclic twinned crystals of chrysoberyl. This sample is about 8 cm across and is from Minas Gerais, Brazil.

At right is the Maharani Cat's Eye, a 58.2 carat chrysoberyl gem which is one of the finest known cat's eyes.