Kautilya's Arthashastra 2.12.1

2.12.1

ākarādhyakṣaḥ śulbadhātuśāstrarasapākamaṇirāgajñas tajjñasakho vā tajjātakarmakaropakaraṇasampannaḥ kiṭṭamūṣāṅgārabhasmaliṅgaṃ vākaraṃ bhūtapūrvam abhutapūrvaṃ vā bhūmiprastararasadhātum atyarthavarṇagauravam ugragandharasaṃ parīkṣeta //

POSSESSED of the knowledge of the science dealing with copper and other minerals (Sulbádhátusástra), experienced in the art of distillation and condensation of mercury (rasapáka) and of testing gems, aided by experts in mineralogy and equipped with mining labourers and necessary instruments, the superintendent of mines shall examine mines which, on account of their containing mineral excrement (kitta), crucibles, charcoal, and ashes, may appear to have been once exploited or which may be newly discovered on plains or mountain-slopes possessing mineral ores, the richness of which can be ascertained by weight, depth of colour, piercing smell, and taste.