The Riddle of Precious Metals: Why a Troy Ounce of Gold Weighs More than a Troy Ounce of Copper but a Troy Pound of Gold Weighs Less Than a Troy Pound of Copper
It might seem confusing at first, but understanding the differences between weight measurements such as troy ounces and avoirdupois ounces can clarify many of the common misconceptions about the weight of precious metals like gold and copper. This article aims to demystify and provide a clear explanation of why a troy ounce of gold weighs more than a troy ounce of copper, yet a troy pound of gold weighs less than a troy pound of copper.
Understanding Troy and Avoirdupois Ounces
When discussing precious metals, it is crucial to know that ounces are not all created equal. There are both troy ounces and avoirdupois ounces, and they are not interchangeable. The Wikipedia entry on ounce provides this important distinction. The troy ounce, used primarily for precious metals, is not to be confused with the avoirdupois ounce, which is commonly used for everyday measurements.
Why Wikipedia Stated It Incorrectly
Wikipedia initially stated that an ounce of gold weighs more than an ounce of copper but a pound of gold weighs less than a pound of copper, which is incorrect. This misconception arises from the difference in the weight of these units. A key point to note is that the troy system is specifically used for valuable materials such as gold, silver, and platinum. In the troy system, each unit of weight is greater than its avoirdupois equivalent. For instance, a troy ounce is 1.097 avoirdupois ounces.
Explaining the Weight Difference
The confusion can be explained by the fact that the troy system defines a troy ounce as 31.1034768 grams, while a regular avoirdupois ounce is 28.3495 grams. Consequently, there are 12 troy ounces in a troy pound and 16 avoirdupois ounces in an avoirdupois pound.
Converting Between Systems
Converting between troy ounces and avoirdupois ounces can help clarify these differences. Here are some key values:
1 troy ounce 31.1034768 grams 1 avoirdupois ounce 28.3495 grams 1 troy pound 373.24 grams (12 troy ounces) 1 avoirdupois pound 453.592 grams (16 avoirdupois ounces)Using these values, we can calculate that a troy pound (373.24 grams) weighs less than an avoirdupois pound (453.592 grams). This is why a troy pound of gold weighs less than a similar weight in copper, despite the troy ounce of gold weighing more than the troy ounce of copper.
The Origins and Usage of Different Systems
The use of different systems for precious metals dates back to the Middle Ages. This choice was made due to practical needs and trade standards of the time. However, this can lead to confusion today, especially for those not familiar with these historical systems.
People in the precious metals industry have simply adapted to using troy measurements and converting to grams when needed. This conversion can be done effortlessly with the above values.
Conclusion
In conclusion, the differences between troy and avoirdupois measurements highlight an important distinction in how we measure precious metals and everyday items. Understanding these units and their conversions can help demystify expressions like 'an ounce of gold is heavier than an ounce of copper' but 'a pound of gold weighs less than a pound of copper.'
By embracing the troy system, we can ensure clarity when discussing precious metals in trade, industry, and investment. While the metric system offers a simpler and more universal approach to weight measurement, the troy system remains essential for maintaining historical and practical standards in the precious metals industry.
For further clarity and additional resources, consider exploring guides and discussions on platforms like Quora or by consulting official documents from organizations specializing in precious metals.