GLAUBERITE     

THIS IS A RARE OPAL PINEAPPLE ONLY FOUND IN WHITE CLIFFS NSW AUSTRALIA.

THERE HAVE ONLY BEEN BETWEEN 300-500 SUCH SPECIMENS FOUND THERE. THEY ARE FORMED AS A RESULT OF PRECIOUS OPAL REPLACING GLAUBERITE [A SULFATE MINERAL] -SUCH SPECIMENS ARE KNOWN AS PSEUDOMORPHS. AS THEY STILL EXHIBIT THE EXTERNAL CRYSTAL FORM THEY HAVE REPLACED. THE GLAUBERITE CRYSTAL IS BELIEVED TO HAVE FORMED UNDER GLACIAL CONDITION WHICH LATER DISSOLVED LEAVING THE VOID TO BE FILLED WITH OPAL THE PSEUDOMORPHS ARE FORMED IN THE PINEAPPLE BAND NEAR THE OPAL FEEDER WITH LESSER -SHAPED PIECES FURTHER AWAY ,THIS SPECIMEN NEED TO BE EXPOSED FOR COLOUR -

MAUVE BLUE 

One of the rarest and most fascinating types of opal comes in the shape of a palm-sized cluster of radiating points that resembles a pineapple. These "Opal Pineapples" are found only in the Cretaceous sediments of the White Cliffs in Australia

White Cliffs is the only place where these marvelous (and very rare) pseudomorphic “pineapple” opals have been found. They were formed when a mineral crystal of glauberite (or ikalite) was first replaced by calcite and then opalised.

Formula: SiO₂•nH₂O
Colour: Colorless, white, various
Hardness: 5½ - 6½

A pseudomorph (which means false shape in Latin) is a mineral that has replaced another mineral's chemistry or structure with its own without changing the outward shape of the original mineral while color, hardness, and other properties change to those of the replacing mineral. Transformations from one mineral to another are not unusual in nature, but preserving the outward shape of the original mineral is! The end result is that the crystal appears to be one mineral but is actually another.

Opal "Pineapples" - an opal pseudomorph formed by the replacement of glauberite by opal - found only in New South Wales.