Kalle Lappinen went out with his metal detector looking for clues that could help prove an Iron Age site existed in the area. What he found instead was far more extraordinary: thousands of pieces of silver buried beneath the Finnish ground.

The discovery, made near the town of Sysmä on Sept. 3, is now recognized as the largest Viking-era silver coin cache known in Finland. According to Lahti Museums, the hoard weighs approximately 4.5 kilograms (nearly 10 pounds), although archaeologists have not yet finished cleaning, sorting and counting everything inside.

For Lappinen, the moment came as a surprise.

He told ABC News that he first felt “disbelief” when he found the silver, followed by a rush of adrenaline because of the significance of the discovery.

And there was plenty to be excited about.

Lahti Museums said the cache wasn't simply a collection of old coins. Along with the silver coins, archaeologists recovered several other silver objects, including a silver bracelet, a silver fragment, a silver clasp and a silver bead.

(Courtesy of Esko Tikkala, Lahti Museums)

The hoard also contains “payment silver” in the form of hack silver, or pieces of silver that could be cut into smaller portions and used for payments according to their weight. Live Science reported that the precious metal alone would put the hoard's modern value at almost $10,000.

The objects had been hidden in two containers, buried about 45 centimeters (18 inches) underground between stones. The two deposits were roughly 12 meters (40 feet) apart.

According to Lahti Museums, archaeologists inspected the site the day after Lappinen's discovery and recovered the cache under the direction of Esko Tikkala, an archaeologist with the regional museum.

The sheer number of coins is still being determined.

“They are quite a lot of coins in this hoard,” Tikkala told Live Science. “I have not had time to go through them.”

Lahti Museums said there are thousands of coins, but their exact number and more precise dating will only become clear after further research.

A Buried Fortune From a Distant World

The coins appear to date broadly to the period between A.D. 1000 and 1050. Some came from areas corresponding to present-day Germany, Sweden and Great Britain, while others were silver dirhams made in the Islamic world.

That mixture of coins, jewelry and hack silver offers a glimpse into a time when silver could travel long distances and be used in different forms of trade.

(Courtesy of Esko Tikkala, Lahti Museums)

And there is still a basic question no one can answer with certainty: Why was all of it buried?

Tikkala told ABC News that one possibility is that a merchant hid the silver for safekeeping. Another is that a wealthy person buried it in case of an attack.

For now, those remain possibilities rather than established facts.

Not Necessarily Buried by Vikings

There is also an interesting distinction behind the phrase “Viking Age.”

Although the hoard dates to what historians call the Viking Age, that doesn't necessarily mean Vikings buried it. Tikkala told Live Science that the term refers to a historical period and does not mean that Finland was culturally or politically part of Viking Scandinavia.

In fact, archaeological evidence suggests that the area around present-day Sysmä may once have been a busy center with numerous trade connections during the Iron Age, even though it is now a modest community.

(Courtesy of Esko Tikkala, Lahti Museums)

Lahti Museums noted that the new discovery also replaces an older record. Until now, Finland's largest known Viking Age money cache was the hoard discovered at Nousiainen in 1895. That earlier hoard contained approximately 1,700 coins and other objects and weighed about 2.2 kilograms—roughly half the weight of the newly discovered cache.

Lappinen said he normally searches for artifacts that can help establish the existence of an Iron Age site. Finding a hoard like this, he told ABC News, is an exception—and one he described as “fascinating.”

Now the real work begins.

Lahti Museums said the coins still need to be properly cleaned, separated and counted, meaning researchers don't yet know the exact size of the cache or its more precise dating.

For more than a thousand years, the silver remained hidden beneath the Finnish soil.

Then, on an ordinary day of searching with a metal detector, Lappinen happened to find it.

And what began as a search for evidence of an ancient settlement has opened the door to one of Finland's most remarkable archaeological discoveries.

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