Opal 'pineapple' Click to enlarge image
Opal replacement of ikaite crystals (opal pineapple), White Cliffs New South Wales Registration Number: D.50628 Image: Carl Bento
© Australian Museum

This opal ‘pineapple’ has nothing to do with the fruit – the term is only a visual description. The opal is made of silicon dioxide with water.

Specimen details

  • Origin

    White Cliffs, New South Wales, Australia

  • Size

    7 x 8 x 8 cm

  • Date

    Registered 1996

  • Collection number


  • Collection

This unusual pineapple-shaped object is thought to be a replacement (or pseudomorph) of one mineral by another before becoming an opal. Once thought to be a replacement of glauberite (sodium sulphate), it is now thought to be a replacement of crystals of the water-bearing calcium carbonate, ikaite. Ikaite only grows under very cold, glacial conditions and then rapidly changes to waterless calcite. The calcite in this specimen was then replaced by purple and green-blue opal.

Opal ‘pineapples’ with their distinctive radiating pointed forms, are only found at the White Cliffs opal field. These curiosities are very valuable and are much prized by collectors. Albert Chapman purchased this specimen in the 1930s.

Discover the Minerals Gallery

Be dazzled by the finest examples from this incredible Australian Museum collection and immerse yourself in the world-leading mineralogy research of the Australian Museum Research Institute.

Now open.

Find out more

Jelly opal

Andamooka, South Australia, Australia. 4.5 x 5 x 2.5 cm. D.50438. Albert Chapman Collection.

Jelly Opal D.50438
Jelly Opal. Andamooka, South Australia, Australia.. 4.5 x 5 x 2.5 cm. , D.50438. Albert Chapman Collection. Image: Carl Bento
© Australian Museum