Here we go again.

A Danish art conservator claims that the controversial Vinland Map of America, published prior to Christopher Columbus's landfall, may not be a forgery after all.

"We have so far found no reason to believe that the Vinland Map is the result of a modern forgery," says René Larsen of the Royal Danish Academy of Fine Arts. Reuters first publicized his results last week but provided none of the skepticism being voiced by veterans in the field.

The map mysteriously emerged in a Geneva bookshop in 1957 depicting a "new" and "fertile" land to the west that Viking explorer Leif Eriksson had christened Vinland. Eriksson's 11th-century voyages to Newfoundland are well-known today, but they were thought to be unknown to 15th-century Europeans. The Vinland map could represent the earliest cartographic record of North America and prove that Europeans were aware of the continent prior to Columbus's voyage.

But scientific experts have bickered over the map's authenticity since the 1970s, as described in a 2004 Scientific American article. The map's parchment dates to circa 1434, but scientists say that the underlying yellow-brown ink has a chemical component, anatase, that indicates a 20th-century origin.

In the new study, presented at the 2009 International Conference on the History of Cartography in Copenhagen, Larsen proposed a possible explanation for the ink's anatase. He suggested the mineral comes from gneiss rocks in the Binnenthal area of Switzerland, which have long been used for sand production. Sand, he explains, was commonly used to dry ink prior to the introduction of blotter paper: "You often find remains of it in old books and manuscripts."

But Kenneth Towe, a retired geologist from the Smithsonian National Museum of Natural History in Washington, D.C., who has followed the issue for many years, says that Larsen is a "serious" researcher but his explanation is "bogus."

"The problem is if the anatase…came out of gneiss or any other natural source, it is going to have a totally different appearance than the anatase that appears on the Vinland map ink," he notes. Towe says the Vinland ink has small round crystals produced chemically, whereas sand would have larger fractured crystals from grinding along with other minerals like quartz. "Even if sand has been found on other maps," he adds, "it still has never been found on the Vinland Map."

Larsen responds he has not looked at the crystals himself but suggests that the sand has been through a "cleaning" that leaves only the smallest crystals. He also claims that the yellow-brown marks are actually a residue left behind after black ink flaked off the map, calling into question the findings that the anatase was only found in yellow ink.

The only thing that is certain, Towe says, is this won't be the end of the Vinland controversy. "This thing has a life of it's own," he says.