1. Mix a small amount of powdered mineral with a bit of powdered charcoal and some sodium carbonate flux, then place some of the mixture on a charcoal block and apply the blowpipe flame, continue to heat the mixture until effervescence ceases, now place a tiny bit of the mixture on a clean silver coin or a strip of silver foil and add a tiny drop of distilled water to it; a black stain composed of Ag₂S will quickly form on the surface of the silver.