Burkina Faso Turquoise Old Marriage Fashion Gold Jewellery Earring Necklace.
By Aamir Mannan.
A reading of 1.61–1.65 (birefringence 0.040, biaxial positive) has been taken from rare single crystals. An absorption spectrum may also be obtained with a hand-held spectroscope, revealing a line at 432 nanometres and a weak band at 460 nanometres
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