Minerals and Metals in Ancient India v2.c43.s3.t4.8

v2.c43.s3.t4.8

The family of beryl is a cyclosilicate Be₃Al₂Si₆O₁₈ which crystallises in the hexagonal system, sometimes occurring as long six-sided prisms, terminated by a basal plane (vide Kālidāsa’s long grass-green *ratnaśalākā* mentioned before). In pure form, beryl is colourless. Lattice sustitution by a very small quantity of chromium (in the form of Cr³⁺) makes the crystal light grass-green (typical *vaidūrya* of the early Sanskrit literature). Larger proportion of chromium (typically 0.2 per cent or above) results in intense green colour: ‘beautiful and deep emerald-green to grass-green, unrivalled in depth and brilliancy and comparable to the fresh green of a meadow in spring’. (Bauer, 1968: 308) This variety is well-known as emerald or *marakata* which was not mentioned by Kautilya, and the best samples were imported later to India probably from Ethiopia, Egypt, and during the Muslim period, from Turkey. Lattice substitution by iron to the extent of 1/2 to 2 per cent makes the crystal light blue, and such natural crystals have been known as aquamarine or *pāribhadra*. Greenish blue *utpalavarna* in *AS*, 2.11.30 an *indīvara śyamavapu utpala* in *Manimālā* (p. 510) is likely to be aquamarine. Ancient India was famous for the light-green as well as light blue beryl/aquamarine, the best supplies originating from Paddur, Kangayam and several other sites in the Coimbatore district. Beryl is also known to occur in yellowish green and pure golden yellow colour.