This large hollow geode lined with sky blue celestine crystals was purchased from a Victorian mineral dealer. Its chemical composition is strontium sulphate. The element strontium in minerals or chemicals has the property of colouring a flame bright crimson red, so is used in fireworks.
This famous deposit was first found in 1967, and many large geodes up to 60 cm in diameter and weighing up to 54 kg have been found. The celestine-bearing layer is up to 30 m thick and is found between limestone layers containing crinoidal (marine animal) fossils and layers of sandy greywacke rock, deposited 65 million years ago.
Sakoany, Mahajanga Province, Republic of Madagascar
23 x 23 x 12 cm
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