Metallurgy is a secret science. It not only evaluates ores that have been mined, but also serves as the foundation of production. Are mining and smelting economical? How long should ores be roasted and annealed?

Fire assaying answers these questions using the available laboratory equipment. After a sample is ground in the mortar, it is put in a pan or alembic along with auxiliary materials and then placed on glowing coals. The sample is roasted, melted, and maltreated in fire.

The results of the experiments vary widely. Do astrology and the seasons influence the gold content of the sample? Does higher heat generate more gold? The skill and faith of the artist are decisive for the success of each undertaking.