Pernicka, one of the world's foremost experts on ancient metals, had come to Penn's archaeology museum last February to rub off microscopic samples from the purported Trojan gold. He would then take them back to Germany for a high-tech analysis.
At best, he thought he might get a rough idea of where the gold had been mined. But where the items had lain for thousands of years, buried in the soil, was likely to remain a mystery.
Then suddenly, a colleague who had come to the lab with Pernicka spotted a clue that apparently no one had noticed in all the decades the museum had owned the jewelry:
Encrusted inside one of the tiny gold loops was a speck of dirt.
The story begins 140 years ago, with another man who was interested in the ancient past.
A wealthy German businessman named Heinrich Schliemann was convinced there was a historical basis for Homer's Iliad, the mythical tale of Greeks fighting Trojans to secure the return of the beautiful Helen.
Unlike Pernicka, he had no formal training as an archaeologist. Still, he traveled to what was then the Ottoman Empire, a copy of The Iliad in hand, determined to find ancient Troy.
On a windy plain near the modern Turkish city of Canakkale, he started to excavate an earthen mound that had been rumored as the site of the ancient city. He dug vigorously through the layers of history, inadvertently destroying some of what he found along the way.
In 1873, he discovered a dazzling assortment of gold, silver, and lapis lazuli. Schliemann proclaimed it the treasure of Priam, the Trojan king whose son marries Helen in Homer's poem, and he received worldwide acclaim.
"I find here a treasure of gold and silver articles, such as is now scarcely to be found in an emperor's palace," he wrote in an 1875 translation of his memoir, Troy and Its Remains.
Among the items was a golden headdress, which Schliemann placed on the head of his wife, Sophia - an act that makes modern archaeologists shudder.
Later research revealed he was wrong, that the objects dated from 1,000 years earlier than any conflict that might have occurred between Greeks and Trojans. Today's academics date Schliemann's finds at 2300 B.C. Even if there was a Priam, this was not his treasure.
Still, archaeologists generally agree that the city Schliemann found was Troy, though his methods smacked somewhat of a treasure hunt.
He removed many of his finds from what is now Turkey without informing the Ottoman authorities, who were outraged when they found out. Schliemann bestowed the Trojan jewelry upon a museum in Berlin; it remained in the city for more than 70 years.
Then, at some point during the chaotic final days of World War II, the controversial golden objects disappeared.
Penn's Museum of Archaeology and Anthropology was founded in 1887, and holds more than one million artifacts in its imposing, burgundy-brick structure on South Street.
Most of the collection was acquired through archaeological expeditions, dating back to the days when gentlemen scholars traipsed across distant continents and sent back their finds by steamship.
But every so often the museum bought from dealers, as it did in 1966.
George Allen of Hesperia Art, a few blocks from Rittenhouse Square, approached the museum with a rare opportunity: the chance to purchase 24 gold pieces that he said were from ancient Troy.
Allen had no evidence to back up his claim that the gold was of Trojan origin, other than what the museum's curators could see with their own eyes. The earrings and other baubles were in the same style as the famous objects found by Schliemann.
The pieces were so similar that initially the curators thought they might be from the Schliemann collection - which was still missing, its loss mourned by art historians worldwide.
In addition, the objects for sale bore tantalizing similarities to golden artifacts from another ancient stronghold: the royal Mesopotamian city of Ur, in what is now Iraq. Scholars already had theorized the existence of a trade network between the two civilizations. The new items, though they lacked a paper trail, seemed to support that theory.
"The purchase of this collection is urgently recommended," Penn curator Rodney Young wrote in a March 1966 memo to the museum's board.
Young also acknowledged that the items had an unsavory aspect, probably having been "looted by peasants and dealers."
Museum officials decided to buy the pieces, for $10,000. But evidently they had misgivings.
Four years later, in 1970, the museum announced it would no longer acquire undocumented objects, arguing that such acquisitions encouraged the "wholesale destruction of archaeological sites."
It was the first museum to take such a stand, and it sparked a worldwide debate in the antiquities field about how best to protect the heritage of the distant past - one that continues to this day.
The United Nations Educational, Scientific and Cultural Organization - UNESCO - drafted a treaty that sought to discourage the purchase of items with a murky history.
Other museums followed Penn's move, though there was resistance from institutions that did not conduct their own expeditions - primarily art museums, which feared cutting off a major source of acquisitions.
Meanwhile, the purported Trojan gold went on display periodically at the Penn museum.
George Bass, one of the curators who had analyzed the collection, told Turkish officials about the museum's purchase, and they came to Philadelphia to see it.
But it was a hollow sort of addition to the museum. As there were no records of their origin, the golden objects had been robbed of their historical and cultural context, their voice.
Then in 1993, all of a sudden some context emerged. Schliemann's treasure turned up.
Lost and found
Confirming reports that had been circulating for several years, Russian officials announced that the original Trojan gold was in the Pushkin Museum of Fine Arts in Moscow.
It had been seized by the Soviet army as war booty and hidden from public view for decades.
Germany demanded it back, as did Turkey, to no avail.
As a result of the gold's reappearance, there was renewed interest in the similar items in Philadelphia.
Russian experts came to compare Penn's items with the Schliemann treasure in Moscow. German scholars, in turn, traveled to the Moscow museum.
The man best suited to sort it all out, perhaps, was Ernst Pernicka.
A professor at the University of Tübingen, in southern Germany near Stuttgart, Pernicka is the director of the modern-day excavations at Troy.
Each summer, he and his colleagues carefully sift through the ruins of a city that endured for thousands of years, on the dry, windy plains of western Turkey, where summer temperatures can reach 120 degrees.
A soft-spoken, gray-haired scholar who leads a team of excavators from 10 countries at Troy, Pernicka does not hog the spotlight.
"You would have no idea from talking to him that he is one of the world's leading archaeological scientists," said C. Brian Rose, a Penn professor who works alongside Pernicka at Troy.
Little by little, the team is piecing together the story of the city, which stood at the crossroads of East and West, its rulers able to charge handsome fees to those who would pass the nearby waterway between the Aegean and Black Seas. It was not the site of one war, as described by Homer, but of many - as revealed in numerous levels of habitation that span centuries.
While the focus is on the excavation, Pernicka was intrigued when, a few years ago, Rose told him about Penn's 24 items reputedly from the same city.
Though Penn's golden jewelry had not been scientifically excavated, Pernicka - who is also a chemist and metallurgist - thought that science might yet fill in some of the missing parts of the story.
Previously, he had applied his analytical techniques to objects such as Celtic gold coins and African ceramic vessels, helping to place them in history and, when necessary, identifying fakes.
Pernicka made plans to visit Philadelphia last year. He would come with Hermann Born, one of the German experts who had been allowed to examine the Schliemann finds in Russia.
He told Rose that an analysis of Penn's artifacts could suggest where the gold had been mined. It also could indicate whether the items belonged together, and were not some sort of hodgepodge from multiple excavations. Or, worse, a forgery.
Meanwhile, Rose, both a curator at the museum and its deputy director, searched Penn's archives for more information about the enigmatic gold. There wasn't much, aside from the 1966 memo urging its purchase.
But like Pernicka, Rose believed that the pieces had been looted.
George Allen, the antiquities dealer who sold the gold to the Penn Museum, died in 1998. But in a telephone interview, his son Ernest recalled that he had a business associate named Hecht.
That's a name familiar to any scholar of the ancient world, and it's associated with controversy. Robert E. Hecht Jr. is a longtime antiquities dealer who has been periodically accused - though never convicted - of selling purloined artifacts. Now 90, he is on trial in Rome on charges of conspiring to sell looted items. He has denied any wrongdoing.
Under pressure from Italian authorities, the Metropolitan Museum of Art in New York two years ago returned one item it had purchased from Hecht in 1972 - a painted vessel known as the Euphronios krater, one of the most famous objects in the ancient art world. Authorities found evidence that it had been looted from a tomb in Italy and had passed through another dealer's hands before Hecht's.
In a letter and subsequent telephone interview last year from his apartment in Paris, Hecht confirmed that he was indeed the source of Penn's Trojan-style gold, with Allen acting as his agent.
Hecht easily recalled the pieces and proclaimed them "beautiful." He said he had purchased them from another dealer, George Zakos, who is dead.
Hecht, a Haverford College graduate and scion of the Hecht department-store clan, said he had "no idea" whether the gold had been excavated legally. He said Zakos, who lived in Switzerland, had not shared the objects' history.
"He didn't say, and I didn't ask," Hecht said. "I thought it was beautiful, and I thought it was genuine."
Asked if the lack of documentation deprived the items of important context, he said no.
"The main thing is the beauty of the thing," Hecht said. "The Venus de Milo, whether it came from the east side or the west side of the island doesn't really change its appeal to the modern world, I think."
As for Penn's collection, "undoubtedly it came from that part of the world, whether it was Troy, or 60 miles away, or 100 miles away," Hecht said.
That is exactly the kind of attitude that concerns archaeologists, who are as meticulous about preserving their sites as a police detective at a crime scene. To a detective of the past, an object's exact location reveals rich detail about its age, its purpose, its owners - its context.
With those avenues closed to him for the supposed Trojan gold, Pernicka turned to mass spectrometry.
Pernicka came last February with his colleague Born, who is head of conservation at the Museum of Pre- and Early History in Berlin.
In a lab at the museum in Philadelphia, Born examined the items with a microscope, looking for tool marks and other telltale signs of ancient manufacture. Right away, one characteristic jumped out:
Some of the artifacts were made from gold wire with an unusual shape. The wire was not rounded, in the form of a long, thin cylinder, but instead had squared-off edges. It seemed to have been made by slicing a flat piece of gold into strips - a technique Born knew had been used in ancient times.
Meanwhile, Pernicka painstakingly removed minute samples of gold from each artifact, in a way that would leave no trace visible to the eye. He rubbed the gold with a small, rough-surfaced quartz rod, removing at most a few millionths of an ounce of metal from each item.
In several places, where rubbing might have damaged an object, he worked instead with a small scalpel.
Pernicka was awed when he beheld the ancient handiwork. He noted that one necklace was strung with handmade gold beads measuring barely 1 millimeter across. Another item featured hundreds of tiny golden chain links.
"It is incredible," Pernicka said, trying to envision how a craftsman could create such things. "You would need tweezers and a magnifying glass."
Then the visiting scholars got a stroke of luck. Born found dirt lodged inside a tiny loop of gold on the back of one pendant - still there, evidently, from wherever it had been excavated.
It was a valuable source of information. Pernicka knew he could analyze the soil, perhaps telling him something about where the gold items had been buried.
Pernicka took the samples back to Germany. If his hypothesis was correct, the gold was alluvial, meaning it had been mined from a river, and thus would contain a mixture of other elements as well.
Alluvial gold figures strongly in ancient legend. King Midas was said to have turned a river to gold by bathing in it.
And the ancients sometimes mined such gold by holding a sheepskin in the water, a method thought to have inspired the tale of Jason and the Golden Fleece.
Back in Germany, the metal samples were analyzed with mass spectrometry. They were dissolved in acid and subjected to a plasma flame, producing metallic ions that were forced through a tube. The ions took different paths depending on their mass - in such a way that Pernicka could measure just how much gold, silver, platinum, and other elements were in the samples.
He also tested the small sample of soil.
The analysis was conducted in the spring and reviewed over the summer; Pernicka plans to publish the findings this year. He was able to compare them with his results from testing a few stray items of the Schliemann gold that remained in Berlin - apparently overlooked by the Russians in 1945.
The 24 pieces from Philadelphia all appeared to be of ancient manufacture. And they were indeed consistent with the gold Schliemann had excavated at Troy in the 1870s.
The gold in both collections was far from pure - containing as much as a third silver. Even more distinctive was the fact that both contained small but significant amounts of platinum - roughly 100 to 200 parts per million, suggesting the metal might even have been mined from the same river.
Also similar were the ratios between the amount of platinum and another metal, palladium.
"This points to the same geological source," Pernicka said.
That doesn't necessarily mean anything about where Penn's jewelry was made, who wore it, and where it was excavated, he said.
The analysis of the soil, on the other hand, provided information from the artifacts' resting place. Using a technique called neutron activation, Pernicka revealed the amounts of a wide array of elements contained in the dirt, from arsenic to zinc.
His finding: The composition was consistent with the soil in the Trojan plain. In particular, the dirt from the gold pendant contained a high level of arsenic - about 40 parts per million.
It was not proof of anything, but Pernicka said it was a good bet that Penn's enigmatic collection had come from somewhere in the region of Trojan influence: Turkey, Greece, or southeastern Europe.
More than 4,000 years after the jewelry is believed to have been buried, even though it had been taken from the ground without care, science had filled in some of the missing story.
"It's astounding," said Rose, the museum curator.
Twenty of the 24 pieces are on loan to the Bowers Museum in Santa Ana, Calif., where they were viewed this month by attendees of the Archaeological Institute of America's annual conference. The other four - golden pendants - remain at Penn, exhibited alongside the Mesopotamian artifacts whose stylistic similarity had intrigued the museum's curators in 1966.
That similarity - highlighted in the exhibit, called "Iraq's Ancient Past" - intrigues Pernicka as well. He has told museum officials that he would like to test the Mesopotamian gold.
That famous civilization had few of its own natural resources and would have had to import gold and other metals. Could the gold have come from Troy? Could itinerant craftsmen or traders have traveled back and forth between Troy and Mesopotamia long ago?
Someday also, if authorities are willing, Pernicka would like to test the Schliemann gold that remains in Moscow. He acknowledged that some Germans would like to see that treasure returned to Germany.
But as a scientist, Pernicka said his primary goal was the pursuit of knowledge.
And in that quest, he said:
"We are now only at the beginning."
Contact staff writer Tom Avril at 215-854-2430 or firstname.lastname@example.org.