Gold has always been one of the most sought-after and valuable precious metals in the world. It has been used in the manufacturing of coins, jewelry, ornaments and decorations for thousands of years. Although lately the price of gold has been on a roller coaster, most experts agree that gold will remain one of the world’s most precious metals.
Gold isn’t the only metal to be prized throughout the ages. Copper is also one of the oldest and most useful metals known to man. According to the U.S. Geological Survey (USGS) Fact Sheet, Copper – A Metal for the Ages, copper was first used in coins and ornaments starting about 8000 B.C. The emergence of copper tools is credited for helping mankind transition out of the Stone Age at about 5500 B.C. The period that followed is sometimes known as the Copper Age, or the Chalcolithic Age. The discovery that alloying copper with tin produces bronze launched the Bronze Age at about 3000 B.C.
Another ancient metal that few people are familiar with is orichalcum, which was mentioned by the Greek philosopher Plato in his writings. According to legend, this metal came from Atlantis and it was widely believed to be as mythical as its city of origin until last year, when 39 ingots of orichalcum were recovered from the ocean floor near Sicily. The treasure is believed to have come from a sunken ship traveling from Greece or Asia Minor.
According to a Discovery News article, today most scholars agree orichalcum is a brass-like alloy, produced by the reaction of zinc ore, charcoal and copper metal in a crucible. When the 39 ingots were analyzed with X-ray fluorescence (XRF), they turned out to be an alloy made with 75-80% copper, 15-20% zinc, and small percentages of nickel, lead and iron.
XRF technology is the gold-standard for accurate, nondestructive elemental analysis in a wide range of applications, including metal analysis. XRF analyzers determine the chemistry of a sample by measuring the fluorescent (or secondary) X-ray emitted from a sample when it is excited by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic fluorescent X-rays (“a fingerprint”) that is unique for that specific element, which is why XRF spectroscopy is an excellent technology for qualitative and quantitative analysis of material composition.
Analysis of precious metals of any kind must be performed with the highest precision and accuracy; even a small error can be quite expensive, depending on the metal and the current market. High power wavelength dispersive X-ray fluorescence (WDXRF) is one of the primary methods for quality control in gold analysis. Read the application note describing the results of precision tests conducted on gold alloys using a WDXRF instrument.