What makes a metal precious?

For a metal to be classified as a precious metal, three factors must be considered:

1. It must be a naturally occurring metallic element: Gold, silver, platinum, and even unusual precious metals like osmium are all metals that exist chemically in nature. Unstable elements that must be created in a laboratory (usually by melting or irradiating other elements) can never be considered precious metals. Therefore, the naturalness and purity of metallic elements is one of the reasons why they are precious.

2. It must be rare: For a metal to be considered a precious metal, the amount of it found in the Earth’s crust must be very small. For example, copper is traditionally used in coinage and jewelry, but it cannot be considered a precious metal. Aluminum was once considered a precious metal because it was almost impossible to refine. However, modern aluminum production and recycling techniques have relegated it to the status of a common metal.

3. It must be valuable: A metal may have both of the previous options, but if it does not have industrial uses and is not well-known to the public, it cannot be classified as a precious metal. Gold and silver are highly sought after as currency, as bullion, and for making precious objects and art. They are also used in the electronics industry. Metals such as palladium and platinum, although not used in jewelry and not as well-known to the public as gold and silver, are used by automakers to make catalytic converters.

A metal must have all three aspects to be valuable. In general, you can get a good idea of ​​its value by comparing a metal with other metals in international markets. Precious metals are actually very rare and very useful. Gold and platinum are definitely considered top contenders. Silver may be more useful industrially, but it is less valuable because it is not as rare as other metals. Rhodium, iridium, and ruthenium are perhaps the rarest precious metals. However, rhodium is usually sold for slightly less than platinum.

How many precious metals are there on Earth?

Here, we will only look at the amount of these precious metals in the Earth’s crust, as it is unlikely that the useful and industrial amounts extracted from the entire Earth’s crust and mantle at this time would be underestimated. Access to the deep Earth, such as the mantle and core, for gold and other metals has so far been impossible. So the vast quantities of these metals in those areas can be ignored. The rarity of a metal is best expressed as its “mass fraction,” or how many kilograms are expected to be present per billion kilograms of material in the crust. Of course, metals are not evenly distributed across the Earth’s surface, or they may be impossible to extract from some areas. The general proportions of precious metals in the Earth’s crust are as follows:

Gold – 4 parts per billion

Silver – 75 parts per billion

Platinum – 5 parts per billion

Osmium – 1.5 parts per billion

Other platinum group metals – 1 part per billion or less
Since the mass of the Earth’s crust is estimated to be about 2.6 1022 kilograms, this means that there are about 400 billion kilograms of gold in the entire crust. Of course, much of it will never actually be available.

How much gold has been mined from the Earth’s crust in total?

Gold is usually measured in troy ounces, so it’s worth noting that 32.15 ounces equal one kilogram. Total global gold production is approximately 1.5 million kilograms per year. Of course, gold has been mined for thousands of years, and the amount has not been as precise as it is today. Experts estimate that about 10 billion troy ounces of gold, or just over 311 million kilograms, have been mined from the Earth’s crust in human history.

How much silver has been mined and how much remains?

Using the same estimates, there are approximately 7.5 trillion kilograms of silver in the entire Earth’s crust. To date, about 1.4 billion kilograms of silver have been mined from the Earth’s crust throughout human history. However, silver corrodes and can be lost over time. Of what has been mined, only 777 million kilograms still exist.