Assaying

Assay: in metallurgy, to analyze the specific qualities, such as weight, measure, and purity, in precious metal.

 

Assaying expertise

Assaying, in chemical analysis, is the process of determining the proportions of the precious metal in ores and metallurgical products.

There are many techniques used to analyze metals, but the technique that is still used today dates back to ancient alchemists, who applied heat to base metals and minerals to establish the quality of the raw material.

The most common assaying technique – fire assaying – for gold, silver, and lead usually consists of six steps:
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1- Sampling

A representative proportion, or sample, is taken.
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2- Fusion

The sample is melted in a crucible (a vessel used for melting and calcining a substance) with suitable fluxes and other agents so that droplets of lead collect the precious metal and drop through the sample into the crucible. The cooled lead alloy forms a metallic “button”. The slag is discarded.

3- Cupellation

The button is melted to oxidize the impurities, including lead and other metals. The silver melts and dissolves the other precious metals, forming a “bead” of silver, gold, and platinum metals sometimes referred to as dore.

4- Weighing

The bead is weighed to determine the total of gold and silver (platinum metals require a different assaying technique).

5- Parting

The bead is treated with hot dilute nitric acid to dissolve the silver. If the gold content of the bead is known to be higher than 25 percent, its concentration is first reduced by adding silver in a procedure known as “inquartation”.

6- Weighing

The gold remnant is weighed and subtracted from the gold-silver bead weight to give the weight of silver.
Italgold Refinery uses more than just fire assaying to determine the quality of your product.

Modern assaying techniques are applied using sophisticated technology in our laboratory.

  • Fire & Chemical Assays
  • Inductively Coupled Plasma Spectrometry (ICP) analysis
  • Atomic Absorption Spectroscopy (AAS) analysis
  • X-Ray Fluorescence (XRF) Spectrometry analysis

Assaying is an important part of the valuation process for your bullion, ingot, coins, or other forms of precious metal. Laws require that items are tested before hallmarking.