At MGS, we offer a wide range of assay services. Since they all do the same thing in the end (determine precious metal purity), some of our customers can be confused about the differences between them and which is best for their particular lot. Here, we’ll lay out the assays we offer to help you figure out which is best for your situation.
Hand/Scratch Test – The scratch test is fast, accurate, and non-destructive. It is best for when you have many scrap pieces to go through, or if the item being assayed has a lot of intrinsic value. It’s accurate within at least 20 parts per thousand. It’s not recommended for use on bullion or white gold items.
X-ray Fluorescence – This test is very accurate and produces computer-printed results, which are handy for authentication purposes. An X-ray assay works well on samples with large flat surfaces. However, it is not recommended for testing items with chemical surface treatment or electroplating. These can give false results in the analysis because only the outermost surface is tested.
Fire Assay – If you want the greatest accuracy, the fire assay can’t be beat. However, it can take more than a day to complete because the sample needs to be melted down as part of the test. A fire assay is best for getting the most value out of large scrap lots. At MGS, we have a $25 charge on fire assays.
Ultrasound Assay – This assay uses an ultrasonic pulse on a sample to detect changes in the consistency of the metal. It is recommended for use on pure samples of uniform structure. This makes it the ideal test for authenticating bullion.
Any miner who knows mining history knows that the Romans made some of the most important contributions to field. In fact, their ability to effectively exploit the mineral richness of Roman Britain was one of the main reasons they were so successful.
One major mining site of the Roman Empire was the Dolaucothi Gold Mines located in present day Wales. To prospect the gold veins in the area, the Romans built aqueducts and large tanks at the tops of hills. They would use massive amounts of water from these structures to wash away ground and expose quartzite and gold ore. When suitable veins were found they would use fire-setting, which involved heating the rock’s surface with fire then dousing it with water – causing the rock to fracture from thermal shock.
Once the gold veins were broken up, the area would become an open pit mine. Ore removed from the mine would be crushed by hammers powered by an ingenious water wheel. The resulting dust could then be washed and sieved to retrieve any gold – which was smelted into ingots and sent all over the empire. For centuries, it was the largest mining operation in the world.
Late last year, EurasiaNet.org ran an interesting article about an illegal gold mine sustaining a remote village near the Naryn Province of Kyrgyzstan.
Private mining in the country is currently illegal. With gold mining activity becoming increasingly contentious and politicized in Kyrgyzstan, villagers would only speak to the press under anonymity. Professionals in the mining industry know that mining is hard work that requires heavy equipment and chemical facilities. With virtually no official support, just how is this village using the mine?
Villagers make a three hour trip to the mining area where they scour the Kyrgyz mountainside for quartz and pyrite – typical geological indicators of nearby gold. They dig up the area and haul promising looking samples of ore back to the village.
In a makeshift refinery, one machine crushes the ore and electric sieves wash away the gangue – leaving the most gold-rich parts. Refining this ore to extract the gold is the most complex (and dangerous) step. Using black market nitric acid, the village’s amateur chemists set up a stainless dish downwind and mix the ore and acid together to dissolve any non-precious metals. The smoke produced from the reaction goes from black, to yellow, to white – which indicates the process is finished.
The miners use the Internet to keep track of precious metal prices and sell the gold to support the village. This has led to the mine becoming a major source of the village’s income. However, no one is sure how long the mine will last.