Wonder Well, Riverina Station, Menzies Shire, Western Australia, Australia
46 km west of the town of Menzies.Prismatic emerald crystals up to 2 cm long are found in phlogopite rock formed as the result of potassium metasomatic alteration of schistose ultramafic rocks intruded by pegmatites. Three generations of beryl are recognized at the deposit: low alkali colourless, light coloured, and bluish green crystals characteristic of pegmatites; dark green emeralds in the phlogopite rocks; pale green beryls with high alkalis and low chromium content. Distinctly zoned crystals with colourless cores and deep green rims are encountered in quartz-albite aggregates. Solid inclusions are predominantly phlogopite and tremolite. The density is 2.71 - 2.75 g/cm³.
Ref: E.Ya. Kievlenko (2003) Geology of gems, p. 95