Sample Analysis

Once preparation is complete, samples can be analyzed for metals content. Most samples will follow one of two analytical processes: wet geochemistry for a broad spectrum of elements, or fire assay for precious metals, both of which are described here.

Pre-Operations Checks

Reagents, fluxes, crucibles and cupels: Vendor prepared flux batches are tested for gold before client samples are analyzed.  Results from 6 tests are determined with method Au-OES30 that has a detection limit of 0.001 ppm.  Tests also confirm crucible and cupel cleanliness.  Reused crucibles are either cleaned by firing them with a cleaning mixture, or by classifying them per their prior assay’s gold concentration. 

Equipment: Fusion furnaces are made by Furnace Industries and the cupellation furnaces are made by Pyradia.  All furnaces utilized by Paragon have dual pyrometers that must remain within tolerance or will indicate a problem code.  Pyrometers must be replaced every 12 months.  

Processing Checks  

Samples are visually and chemically prescreened for flux suitability.   Before adding flux to samples, sample color and chemical reactivity is evaluated.  Reactivity is measured with a droplet of nitric acid on the sample which will indicate which flux amendment to add.

A furnace load is 84 samples or two racks of 42.  Furnace temperatures are examined 15 minutes after sample loading—the fusion time upon which the furnaces’ temperature should recover to its maximum temp.  

Post-fusion indicators are many, and often visually apparent.  Fusion slag clarity, color and brittleness is evaluated, along with the lead buttons’ weights and malleableness.

Post cupellation indicators are found in the residue left on the cupels from the flux lead or other metals, cupel color, and prill weight, color and shininess.

For more information regarding our Fire Assay Prill Digestion 

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