Which mineral has the highest inflation rate?

A new study finds that copper, zinc and iron prices are the most expensive on earth, and the lowest in North America, as well as in the world.

In the study, published in the journal Nature Communications, researchers at The University of Texas at Austin compared the prices of four of the top five mineral commodities—Aluminum, Nickel, Copper and Gold—and compared them to the price of the same commodity in 20 countries around the world in 2013.

Copper and gold prices have been rising steadily in recent years, with copper prices rising by 8.9 percent over the past year, while zinc and copper prices have risen by 5.5 percent.

“Aluminum and copper have historically been the most popular minerals in the U.S., and copper and gold have been in the lead,” the study authors wrote.

“The copper price, for example, has grown by nearly 20 percent over that time, while the copper price has grown just 2.4 percent.”

The study was led by the UTA College of Business Professor Andrew Smith, who specializes in mineral resource economics and is a member of the University of Minnesota’s School of Mineral Resources.

“This study confirms that the price inflation rate of these mineral commodities is highest in the middle of the price distribution in North and South America,” Smith said in a statement.

“In addition, this study provides evidence that this price inflation pattern reflects the nature of the commodities, and is not simply a result of the global economic environment.”

The research was based on data from the International Mineral Price Index (IMPI), a global database of minerals, which collects prices for all mined and untapped resources worldwide.

Smith said the price changes reflect the economic cycle of the past several years.

The data is derived from an index of commodity prices that is based on the prices recorded on major international trading exchanges.

The IMPI is based around three commodities: Copper, Nickel and Gold.

It has a base value of $15.42 per metric ton and a range of prices from $10.23 to $18.83 per metric, according to the website.

In 2013, prices for these three metals grew by 10.5 and 7.5 times respectively, the researchers said.

“There are a lot of things that could be happening that are driving this price change,” Smith told the Associated Press.

“I don’t think that copper is particularly expensive to mine because copper is very expensive to refine.”

Smith said copper prices are typically higher in China because of the country’s high levels of demand for copper, which accounts for roughly 85 percent of the world’s copper supply.

“What we see in the Copper market is that China is very competitive, and copper is really expensive to do business with in the Chinese market,” Smith added.

“China has very high copper prices, and that’s where the price increases are coming from.”

The researchers also examined the mineral prices of other commodity sectors such as coal, oil and natural gas.

While prices in coal are relatively high, Smith said prices in the oil and gas sector are higher.

In particular, prices in oil and the natural gas sector tend to rise when oil prices fall.

“These mineral prices are based on a number of factors,” Smith explained.

“We know that the global energy industry is a very dynamic business and has been for a long time.”

The study authors noted that there is a correlation between price increases and changes in demand for the minerals.

“Copper prices are particularly volatile because of a global supply glut, and this leads to price increases in other mineral commodities,” Smith noted.

“It’s not surprising that prices are higher when copper prices fall, because copper tends to have higher prices when copper price is higher than the other minerals.”

In the long term, Smith says that copper prices will be “under pressure.”

“The mineral price indexes are a very accurate reflection of market demand, but we need to have the market price of copper for the entire world,” he said.

The researchers found that prices for aluminum and zinc fell over time, as was the case for copper.

However, in the short term, zinc prices increased by 3.5 to 5.7 percent over a decade, while prices for copper rose by 3 percent.

Smith told ABC News that zinc prices have historically experienced strong price inflation, with prices increasing by 7.7 to 10.2 percent annually since the mid-1980s.

“That said, I think zinc is going to get a bit of a bump in the long run, and I think the price will go up a little bit as well,” he added.

The report was based in part on data provided by the United States Geological Survey, a government agency.

The University is a national research university affiliated with the National Science Foundation.

Smith and his co-authors were joined by colleagues from the University at Buffalo, the University, the Natural Resources Defense Council, the New York State Geological Survey and the Natural Resource Defense Council.

The study appeared