Ornamental variscite: A new gemstone resource from Western Australia

Variscite (AlPO4.2H2O) is an uncommon bluish-green mineral that has been used as an ornamental gemstone since the Neolithic Age. A new location of variscite has recently been investigated on Woodlands Station, Western Australia. The variscite from here occurs in a variety of aggregated habits within fi ne-grained Proterozoic siltstones and breccias. Rock surfaces have been found encrusted with microcrystals of variscite and wardite. Within the host rocks, associated minerals include metavariscite, crandallite, jarosite, quartz and grains of native gold. The gemmological properties of the Woodlands variscite are: RI range of 1.570 to 1.582, and SG from 2.49 to 2.55, and these are within the ranges of variscite from other world sources. X-ray diffraction analysis confi rms the variscite to be of the ‘Mesbach-type’ in association with metavariscite, a dimorph of variscite. Using visible refl ectance spectroscopy, trivalent chromium was verifi ed as the main chromophore responsible for the colour. Minor vanadium is also present, probably in mixed oxidation states of +3 and +4.