A mammoth emerald has been found in the northeastern Brazilian state of Bahia, weighing about 600lb and standing more than 4ft tall.

Brazil's National Mineral Production Department said the precious stone was discovered in April by miners working for the Bahia Mineral Cooperative and was sold to a local mine owner. The anonymous buyer has plans to have the emerald displayed in museums and other public facilities around the world.

The government and the buyer's representatives did not comment on the value of the stone. A similar stone found in 2001 that weighed 640lb was valued at $300m (£231m), indicating this stone could well fetch hundreds of millions of dollars.

Bahia has been home to some big emeralds including the largest one ever found known as The Bahia Emerald. It was a gigantic stone weighing close to 840lb discovered in 2001. It is not a pretty stone chunk but rather a conglomerate of emerald crystals lodged at odd angles in a matrix of black schist. It contained over 180,000 carats of emeralds, including the largest single shard of emerald ever found, described to be "the size of a man's thigh". The stone was valued for over $400m and its ownership is currently under dispute.

Despite its gigantic size many gemologists have said the Bahia stone is composed of low-quality crystals, calling it a "fish tank emerald".