The word used in Matthew 26:15 (argyria) simply means “silver coins”
There were a few type of coins that may have been used. Tetradrachms of Tyre, usually referred to as Tyrian shekels (14 grams of 94% silver)
Because Roman coinage was only 80% silver, the purer (94% or more) Tyrian shekels were required to pay the temple tax in Jerusalem. The money changers referenced in Matthew 21:12 exchanged Tyrian shekels for common Roman currency.
There are 31.1035 grams per troy ounce. A spot valuation of $16.49/oz (As of 8:30am CST Monday June 4, 2018), 30 “pieces of silver”… Source
The Roman Empire is one of the most well known monetary systems in history. It is also one of the most studied as the long history, and great documentation of how everything worked, has helped anyone with a desire to understand money, currency and economies to come a good understanding of how it works and what happens when a corrupt government begins manipulating the monetary system. One can also see the impact of the Roman government debasing the national currency (like the Federal Reserve has done beginning in 1913) and the devastating effect on society as a whole. Once a currency becomes corrupt the entire system, and society, must become corrupt to hide the lie the currency is telling.
It can be argued that when Spain instituted a common currency in the form of the Real de a Ocho, also known as Pieces of Eight, or the Spanish dollar, globalisation’s first chapter had been written. The acceptance of the dollar coins for commercial transactions throughout Asia, the Americas and much of Europe, resulted in a cultural exchange between nations, as well as the relatively free movement of people and goods between the three continents – Source
The China Connection
China’s insatiable demand for silver led to increased production in the Bolivian highlands and by the late 16th century Cerro de Potosi alone produced an estimated 60 per cent of all silver mined in the world. Source
Many of the products imported into New Spain were highly coveted luxury goods. Silk was popular, both in its raw form and finely embroidered, as was porcelain, diamonds, pearls, ivory and wooden furniture. Cotton from the Philippines, and other parts of Asia, became highly profitable due to the high quality. Other products in demand were spices, tea, Indian linen, amber, swords and knives, potassium nitrate for gunpowder, and mercury, for industrial use to mine silver. Source
This global trade would continue to grow, continue to increase and increase the worlds wealth, especially China’s wealth since they were acquiring all the silver for their manufactured goods. China would continue conducting trade with Spain, and then the U.K., for the next 150+ years. This would lead right into the “opium wars” where the West wanted their silver back, as China had most of the worlds silver supply, but China shutdown trade. So, the retaliation was to begin importing opium into China and the only acceptable currency for the opium was silver.
Enter the United States
When the Founding Fathers of the United States were writing the Constitution they used the bases for the Pieces of Eight as the formula for U.S. Coinage as codified in the Coinage Act of 1792.
Section 19. Penalty on debasing the coins – And be it further enacted, That if any of the gold or silver coins which shall be struck or coined at the said mint shall be debased or made worse as to the proportion of the fine gold or fine silver therein contained, or shall be of less weight or value than the same out to be pursuant to the directions of this act, through the default or with the connivance of any of the officers or persons who shall be employed at the said mint, for the purpose of profit or gain, or otherwise with a fraudulent intent, and if any of the said officers or persons shall embezzle any of the metals which shall at any time be committed to their charge for the purpose of being coined, or any of the coins which shall be struck or coined at the said mint, every such officer or person who shall commit any or either of the said offenses, shall be deemed guilty of felony, and shall suffer death. Source
We would encourage everyone to read How Silver Changed the World which is the inspiration for this article.