What is Diaspore?
Diaspore is an aluminium oxyhydroxide known for pearly cleavage, strong pleochroism and the colour-changing gem variety marketed as Zultanite.
Mineralogy and structure
The reference formula is AlO(OH). Diaspore is one of the principal minerals in the diaspore-boehmite-gibbsite aluminium oxyhydroxide system. Gem material can show green, yellow and pink colour shifts under different light.
Colour and appearance
Typical colours include colourless, white, yellow, green, brown, pink. Its platy, prismatic, massive habit and vitreous, pearly lustre are useful descriptive features, but colour alone is not diagnostic.
Formation and localities
Diaspore forms in or is associated with metamorphic aluminium-rich rocks, bauxite-related deposits and hydrothermal alteration zones. Important documented localities include Turkey, Russia, Hungary, the United States, Brazil and Myanmar.
Collecting and care
Diaspore is best kept as a labelled reference or collector specimen. Protect fragile crystals from impact and avoid cutting or grinding unknown material. Lead-, arsenic-, vanadium- and copper-bearing specimens are for display and careful handling only.
Diaspore in popular symbolism
Some modern crystal guides associate Diaspore with zodiac signs or symbolic themes based on colour, locality or collecting tradition. These associations vary between sources and are cultural interpretations, not mineralogical or medical properties.
