Assay Class

Date: 25-Nov-2017
Capacity: Not Set (Available)


Saturday, November 25th, 2017, 10am and 1pm:

The Gold Assay Process: Magic or Chemistry?

Gold Assay Seminar! Gold does not come out of the ground ready to wear. Join us to discover how ore is processed to extract gold. Hands-on learners of all ages will crush and classify ore as they learn the basics of gold ore assaying--determining the value of gold in the rock. This fast moving, interactive assay demonstration will overview the math, mechanics, and chemistry of this exciting process. Explore Colorado’s rich mining heritage by RSVP-ing to or 719-488-0880 to reserve your seat.  Please RSVP as space is limited!

Recommended for ages 10 and up

Demonstration is included with normal admission prices.

Admission rates: Adults $9, Military/AAA $8, Seniors/Students $7, Children 4-12 $5, FREE to children 3 and under as well as Museum Members!

What is Assaying? Assaying is a process for determining the amount of a certain metal contained in an ore or alloy; it is used to evaluate mineral deposits and to check the composition of ores and alloys. In order to get an assay, the assayer must perform many steps that require exactness and careful attention. Assay reports of ores usually give the percentages of the desired metals contained in the ores. The contents of most alloys are given in percentages, but gold and silver are exceptions. The gold content of an alloy can be stated in terms of fineness (the number of parts of gold in 1,000 parts of alloy) or in karats (the number of parts of gold in 24 parts of alloy). 

The first step in assaying is to obtain a representative sample of the mixture to be tested. Once the sample has been prepared, there are several methods of assaying it. The method chosen depends both on the type of material being assayed and the degree of accuracy required. Fire assay, or dry assaying, has been in use for thousands of years, the standard method in early Colorado mining, and still stands the test of time as a method to value noble metals. Fire Assay is an assay method in which the material is subjected to high heat (as in fusion, scorifying, and cupellation). It is still the most common method used today, mainly on gold and silver ores. Assaying is the process used to determine the weight of metal per ton of ore.

Join WMMI’s very own Christine Nestlerode and special guest, Richard Sweeny for the explanation and demonstration of the assay process!

Mr. Sweeny is the inventor of the UFO Micro Furnace, inventor of Amalgamite, a bimetallic flux used to refine scrap gold and silver, inventor of the Hammerhead impact mill, and inventor of the Uphill Riffle Sluice, the only new sluice design in over a century; and capable of recovering micron gold other sluices miss.