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A mineral's metal content is determined by doing a process called assaying.It is specifically used for gold,silver and platinum ores.
The first step taken into action is to collect a sample from a certain mineral. These samples are either chosen from machines or by hand. Their substance content is then evaluated and if all of their ore content are equal,they are considered as the right samples.
A process known as fire assaying is undergone to try to separate the sample's mineral content and the other useless substances it contains. Per 1 assay ounce of a sample is being mixed with other substances like lead monoxide,silica,soda ash,borax and flour. They are then melted to temperatures up to 1000 degrees centigrade within an hour. After that,they are poured and cooled in an iron mold. The iron mold consists of two parts:the upper one where some quantities of slag settles and are later removed and the bottom part where the other metallic substances consisting of lead alloy button go into.
Lead is then attempted to be separated from gold and silver using a process called cupellation.The alloy button is put into an open container called cupel as the litharge formed during heating penetrates into it.When all the lead is gone,only the pure gold and silver remains called dore bead. The cupel is taken away and cooled for future use while the bead is processed for cleaning from other foreign materials. The gold is then distinguished from the silver which is going to be thinned until no more traces of it are found. This method is called parting.The pure amount of gold for the original mineral is calculated. The difference on how much the gold weighed after it was parted and while it was cupelled with silver constitutes the proportion of silver contained within the gold ore.
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