Pineapple Opal

Pineapple Opal is a rare and famous opal pseudomorph from the White Cliffs field in New South Wales, Australia. It formed when opal replaced clusters of bladed crystals, leaving a distinctive radiating, spiky shape resembling a pineapple.

The original crystals are thought to have been ikaite (or glauberite), which dissolved and were replaced by hydrated silica while retaining the crystal-cluster form.

Specimens may be common opal or, prized highly, precious opal showing play-of-color. Genuine pineapple opals are scarce and command high prices among collectors.

Pineapple Opal began as clusters of bladed mineral crystals, likely ikaite, a cold-water calcium carbonate, or glauberite, growing in the sediments at White Cliffs. As conditions changed, these original crystals dissolved.

Silica-rich groundwater then filled the resulting molds, depositing opal that preserved the radiating, pineapple-like external form, a process called pseudomorphism.

This specific combination of conditions occurred almost uniquely at White Cliffs, which is why genuine pineapple opals are among the rarest of all opal specimens.

Identify Pineapple Opal by its unmistakable three-dimensional cluster of radiating bladed forms, resembling a pineapple or sea urchin, rendered entirely in opal. Hardness is 5.5-6.5, streak white, luster vitreous to waxy.

It may be white-grey common opal or show precious play-of-color.

Its distinctive pseudomorph shape is its key identifier; few other materials mimic it. Provenance from White Cliffs strongly supports authenticity, and the radiating crystal habit replaced by opal is diagnostic.

Pineapple Opal is almost exclusively a collector and museum specimen rather than a jewelry stone, owing to its rarity and unusual three-dimensional form. Fine examples, especially with play-of-color, are among the most coveted opal specimens.

As soft, hydrous opal it must be protected from impacts, heat, and dryness that can cause crazing, and is typically displayed rather than worn.

Its value is driven by rarity, the completeness of the pineapple form, and any play-of-color. Authenticated White Cliffs pineapples are extremely valuable.