CHRYSOBERYL
BY CHISOM IBEMERE
Chrysoberyl gemstone is an aluminate of beryllium which is one of the hardest known natural gemstone. It’s name is gotten from the Greek words “Chrysos” and “Beryllos” which means “a gold-white spar”.
There are three main varieties of Chrysoberyl gemstone which comprises of Ordinary Chrysoberyl, Cat’s eye and Alexandrite. Ordinary Chrysoberyl occurs as yellow-green and transparent gemstone. Alexandrite shows green, red, Orange-yellow which depends on the direction of polarised light. It also varies in artifial light. Cymophane also called the Cat’s eye show Opalescence that resembles the eye of a cat. The three varieties of Chrysoberyl are similar in their chemical composition but optically different.
Chrysoberyl formation occurs as a result of Pegmatite processes. It can be seen in Mica Schists and in contacts with metamorphic deposits of dolomitic marble. As a Beryllium mineral, it only occurs where there are high quantity of beryllium which could hinder it’s geographic distribution and abundance.
Chrysoberyl is a hard and dense gemstone with resistance to chemicals. It has it’s deposits in river sands and gravel in alluvial deposits with other gem minerals through weathering and erosion of rocks.
Chrysoberyl cannot be used as an Ore of beryllium due to its limited deposits and as such majorly used as a Gemstone because of it’s hardness and special qualities of Chatoyance and colour alteration.
Chrysoberyl has been a highly valued mineral for thousands of years in Asia due to the believe to provide protection to the owner/wearer. In recent times, Alexandrite and Cat’s eye remains the most popular Chrysoberyl. It has a vitreous lustre with a hardness of 8.5.
Chrysoberyl is one of the world’s most expensive gemstone and had been sold in recent times for tens of thousands of dollars. It’s deposits can be found in Kogi State of Nigeria.