Russia is the largest country in terms of geographical area. As a result, it has some of the largest mineral reserves in the world. In fact, it ranks in the top three in mineral commodities such as platinum, gold and iron ore. Russia is also the world's largest producer of diamonds and palladium.

Russia's mining industry accounts for a significant share of its gross domestic product and exports. It is the country's second largest industry after oil and gas. But unlike oil and gas, which is primarily state-owned, Russia's mining industry is mostly privately owned. Alrosa (ALRS.ME), which is the world's largest diamond producer, is partially under state control.

Wondering about the largest Russian mining companies? Here are the top four based on revenue and market cap in 2018.

1. Mining and Metallurgical Company Norilsk Nickel (GMKN.ME)

Norilsk Nickel is one of the world's leading producers of nickel and refined nickel. It's also a leading producer of platinum metals, with roughly half of the world's supply of palladium (virtually the total output of that metal in Russia) and nearly the same share of platinum.

Headquartered in Moscow, the company operates mines in five countries: Russia, Botswana, Australia, South Africa and Finland. In 2017, the company reported revenue of $9.15 billion and a net profit of $2.12 billion. The company has a market cap of $25.5 billion as of October 27, 2018.

2. Polyus Gold (PLZL.ME)

Polyus Gold operates five mines in Russia. It is the largest gold producer in Russia and in the top 10 globally, with probable and proven reserves of 68 million ounces. Its Olimpiada and Blagodatnoye mines are among the largest gold mines in the world.

In 2017, Polyus Gold reported revenue of $2.72 billion and profit of $1.24 billion. Polyus has a market cap of $8.33 billion as of October 27, 2018. 

3. Alrosa (ALRS.ME)

This partially state-controlled company is the world's largest diamond producer in terms of output, which hit 39.6 million carats in 2017. The Russian government sold off an 11 percent stake in the company in 2016, valued at $813 million, to cover a budget deficit.

In 2017, the latest year for which figures are available, Alrosa reported revenue of $4.2 billion and net income of $1.2 billion. The company has a market cap as of October 27, 2018, of roughly $10.4 billion.

4. Uralkali (URKA.ME)

Uralkali produces a large percentage of the world's potash supply, controlling the entire production chain, from mining the actual potash ore to supplying potassium chloride to customers. The mining company operates seven plants and five mines in Russia, with subsidiaries in Beijing, Singapore, Panama and Brazil, among others.

The company's 2017 revenue was $2.76 billion, with a net profit of $874.62 million. Uralkali's market cap is $3.75 billion as of October 27, 2018.