On a fog-shrouded dawn, Nov. 17, 1968, the West German freighter Scheersberg chugged out of Antwerp harbor bound for Genoa with 560 drums of uranium oxide in its hold. The boat never reached its planned destination but docked 16 days later in a Turkish port - shorn of its sensitive cargo.

Revelations of the missing uranium were confirmed recently by European Economic Community officials, but the bizarre disappearance at sea of the 200-ton load still remains an enigma spiced with rumours of bold piracy and furtive business dealings.

Despite Israeli denials, most conjecture claims that the Uranium turned up in Israel for use at its nuclear-power facilities in Dimona. But how the shipment got there, if it ever did, still baffles European security experts.

Some sources say that the slightly treated ore - enough to make 30 nuclear bombs - was hijacked in the Mediterranean Sea and rerouted to Isreal's port, Haifa. Other experts, however, point to clues that could indicate that the cargo was secretly intended for Israel all along, aided by commercial complicity in Europe. Yet another guess postulates that the uranium ended up in the hands of Palestinian terrorists.

The key to the riddle of the missing uranium may be wrapped in the uncharted two-week journey between Antwerp and Iskendrun, Turkey, but a number of puzzling questions have surfaced concerning the transaction behind the shipment.

Asmara Chimie, a West German petrochemical company, purchased the uranium oxide from the Brussels-based Societe generale des Minerals for $3.7 million in March 1968. The uranium ore has been mined in Zaire's Shaba Province.

The Sale license stipulated that the cargo was solely intended for "non-nuclear purposes," according to company officials. Under terms of the contract, Asmara would send it to its Milan-based partner, SAICA, to process for use as catalysts in the petrochemical industry.

Three days after the Scheersberg left Antwerp, Asmara canceled its deal with SAICA, which subsequently received $30,000 from Asmara as compensation for the aborted agreement.

When Euratom, the common market nuclear agency, checked on the status of the shipment in January 1969, it received what one EEC official described as "suspiciously vague" replies. After several months of dawdling responses, Euratom launched a special inquiry. West German, Belgian, Italian and U.S. officials also began investigating the Scheerberg odyssey.

Sources here say the Scheersberg crew, and notably its captain, one P. Barrow, were never found and interrogated. U.S. intelligence reports said the ship vanished for a year before turning up in Morocco, but it now seems certain that the Scheesberg docked in a number of European ports during that time, still sailing under the Liberian flag it carried when it left AntwerP.

The separate investigations were apparently closed after a year-long search and the results never published, but portions of the inquires, at times conflicting, have surfaced in the past two weeks.

One intriguing question, EEC sources say, is why Asmara and its managing director at the time, Herbert Scharf, never applied for reimbursement from insurers of the uranium cargo.

The failure to track the lost uranium shipment has riveted attention on the need for strict policing in the transport of nuclear materials in Europe. The security services of Euratom, as well as the nations involved, were not only helpless in preventing the alleged theft but also unable to find out where the uranium went.

Moreover, none of the investigating teams ever determined the full involvement of the various companies that participated in the uranium deal. Euratom officials admit that Asmara's role was never explained satisfactorily.

How the uranium actually vanished also remains open to speculation. One guess is that the cargo was heisted from the Scheersberg in a mid-sea holdup. A more plausible theory, says one Euratom official, is that the ship was simply diverted to a Middle Eastern port and stripped of its uranium load before being sent back to sea.

Since the ship's original crew has not been traced, no solid proof or witnesses have been produced.

Israel denies that it acquired the missing cargo, nating that it could have bought uranium on the world market at the time and thus scarcely felt compelled to risk a daring sea robbery.

The notion that the uranium was hijacked by Arab terrorists has also been floated in Euratom circues. But that guess, like so many others, still founders from lack of evidence.