Assaying Basics

Understanding a refiner’s metal sampling and analysis processes

 

Preparing the Sample

How refiners obtain a sample will depend on the lot. For most metal lots, refiners typically use one of three methods: drill, pin, or dip. To obtain a drill sample, the refining lot is melted down and formed into a bar. A small section is then drilled out of each end of the bar and used as the sample. For a pin sample, the lot is melted down and a glass tube is dipped into the molten metal to draw the sample, which then cools into a pin shape. For a dip sample, the lot is melted down and a small amount is collected and poured into water to create a granulated sample.

Refiners and independent assayers may have their own preferences for which type of sampling to use, but the consensus is that the pin and dip samples tend to be more representative, as they gather a more thorough mix of metals while the sample is still molten. Since lower-grade materials (such as gold under 10k) contain m...