Minerals and Metals in Ancient India v2.c43.s3.t2.7

v2.c43.s3.t2.7

Rose-red balas-ruby belongs to an altogether different category. It is not Al₂O₃ but a spinel or mixed oxide, MgAl₂O₄. It is softer than ruby, its hardness being eight in the Moh’s Scale. Like Al₂O₃, it is colourless when pure, chromium substitution making it red. Spinels come in a wide variety of colours, but here we are concerned with rose-red spinels which have been known as balas-rubies or *rubis balais*. Spinels are abundant in the ruby mines of Badakshan. In the thirteenth century AD, Marco Polo collected spinels with rubies in the province of Balascia on the Upper Oxus, which is identical with the Badakshan of the present-day. Bauer writes (1968: 298) that the term ‘balas-ruby’ is derived from the place-name Balascia. However, we propose that both these names were derived from the Sanskrit term *bālasūryaka*, the crimson-coloured morning sun. Kautilya mentioned *bālasūryaka* as a variety of *padmarāga* or ruby (*AS*, 2.11.29). Thus it is quite likely that ever since Kautilya’s time, the Indians were familiar with the spinel ruby mines of Badakshan. These mines remained famous for more than a millennium. In 1315, Thakkar Pheru wrote: