Minerals and Metals in Ancient India v2.c45.s9.10

v2.c45.s9.10

Tikṣṇam represented in general, carburised iron with appreciable hardness, which could be hypoeutectoid (less than 0.83 per cent carbon) or hypereutectoid (more than 0.83 per cent carbon) steel. *Pogaras* meant hair-like lines which may be surmised as white cementite streaks, coarse enough to be seen by naked eyes (microscope had not been discovered yet). In the *khara* variety, cementite *pogaras* were too fine to be seen, but the brittleness and the ‘mercury-like shining fracture surface’ were evident. In the *hṛnnāla*, *vājira* and *kālāyasa* varieties, hot forging and quenching had resulted in hardness as well as ductility. We have explained this point earlier while discussing the medieval practice of damascening of swords. The *hṛnnāla* variety was *chedane atiparuṣam* very hard to pierce. *Vājira* was described as *pogara vajra samkāśa sūkṣmarekhā* full of hard *pogaras* and overspreaded by dense thin linings. *Kālāyasa* variety was described (5.82) as