SCIENTISTS COME STUDENTS : PERU GLOBAL ESSAY

PERUVIAN PUZZLER : The case of the doubtful dinero. A decade ago, a funny mystery fell into the hands of scientists and students at the Pontifical Catholic University of Peru in Lima.

The university had been acquiring 19th - and 20th - century Peruvian coins from local dealers, and graduate students in the chemistry department were analyzing the pieces for their thesis work.

One coin, a 10-cent piece known as dinero, stood out.

The dinero was marked '' 1899 ''. But official records indicated no coins of that domination had been minted in Peru that year. According to the people who made the money, the coin had never existed.

Most international coin catalogs don't list 1899 dineros, said Luis Ortega, a chemist at the university. And in the rare cases that they do, there is often a note of '' counterfeit '' with no further detail,  Dr.Ortega said. '' No one was able to provide more information about it. ''

Now Dr. Ortega and Fabiola Bravo Hualpa, a doctoral student, believe that they have shed new light on the mystery of the coin that came from nowhere.

In a paper published last year in the Journal Heritage Science, they described subjecting the coin to a barrage of scientific analyses, illuminating its possible origins and the role it might have played in an unstable era of South American History.

To the naked eye, the 1899 coin resembles other dineros : It's silver in color and features the same coat of arms and a seated woman who represents the goddess of Liberty. 

And it's remarkably similar in size to other dineros minted around the turn of the 20th century - about the dimensions of a U.S. dime.

But when Dr, Ortega and Ms. Bravo Hualpa bombarded the 1899 coin with X-rays and measured the light it  re-emitted, they determined that the dinero was largely made of copper, zinc and nickel, an alloy known as nickel silver.

The alloy is commonly used to make silverware and ornamental objects and has a silvery appearance, but it contains no silver, Genuine dineros produced by Lima Mint, on the other hand, are roughly 90 percent silver.

Dr. Ortega and Ms. Bravo Hualpa also found that the 1899 dinero contained traces of iron, cobalt and lead. Such contaminants are characteristic of older alloys because of limitations in older technology.

Given that nickel silver wasn't widely used for coins or tokens in Peru in the 19th century and early 20th centuries, it's likely that this coin was created abroad, the researchers suggest. It's producer might have been wholly unaware that no dineros had been officially minted in 1899.

Dr. Ortega said that an influx of low-value coinage would have been welcomed in Peru at the dawn of the 20th century.  

The government was focusing on printing larger-denomination paper bank notes to pay off international loans; in 1899, the Lima Mint produced roughly one tenth the number of silver coins it had produced just five years earlier.

As a result, people in Peru were using coins from neighbouring nations or even cutting their own country's coins in half to conduct small transactions.

'' Counterfeiters found a field of opportunity,'' Dr. Ortega said.

Dineros were low-denomination coins used by everyday people. Studying this coin, and the economic and political situation that prompted its creation, can therefore be illuminating.

'' If you want to study our society, you don't want to look at a Ferrari,'' said Laura Perucchetti, an archaeo metallurgist at the British Museum in London who wasn't involved in the research. '' You want to look at a Volkswagen or a Ford.''

Dr. Ortega plans to meet with a collector based in Lima who amassed an assortment of coins ostensibly minted from the 1830s through the 1960s. Another 1899 dinero has already surfaced in that collection, and he is on the lookout for more.

'' There must be a few around,'' he said. [ Katherine Kornel ].