This tense, remote government mining town, which broke into news headlines when it was briefly and bloodily captured by rebel invaders more than 18 months ago, is the last financial prop of Zaire's tottering economy.

To the casual observer, Kolwezi has returned to normal. Uniformed schoolchildren stroll the European section in laughing, jostling groups. Competing girls basketball teams draw large crowds in the black neighborhood adjacent to the train yard.

Only a few unrepaired bulletpocked houses and shuttered stores remain to attest to the carnage inflicted on Kolwezi in May 1978.

Hundreds of Africans and approximately 130 Europeans were killed. The long-term stakes were 65 percent of the world's supply of cobalt, a strategic mineral and a large share of its copper.

The vast majority of Zaire's abundant supply of both minerals -- most of which is sold to the United States -- is mined at Kolwezi. Copper and cobalt provide 70 percent of Zaire's $1 billion annual export earnings.

Kolwezi's overwhelming economic importance for the government of the President Mobutu Sese Seko, and the repeated threats to it, have turned the town into an armed camp. At the same time, traditional racial resentments and wage disparities have grown.

Although the mines at Kolwezi are government-owned, Mobutu has been disposing of his country's natural resources in the manner of a 19th century autocrat.

Apart from its normal operations, the government mining company, Gecamines, according to a Western source, provides a lucrative income for about 150 close associates of the president who are kept on the payroll.

Moreover, the world's richest copper and cobalt lode, lying untapped just outside Kolwezi, is 80 percent foreign-owned. One of, if not the most prominent Zairian shareholder, according to sources here, is Mobutu himself.

But it is Kolwezi and the Gecamines operation, with its 1,500-foot-deep mine and six cavernous open pits stretching for 15 miles outside the city, that hold the key to Zaire's future.

Kolwezi is operated like an old American mining town. The African miners' food is brought in by Gecamines from South Africa, and sold at below retail value to subsidize the $50 a month salaries.

European technicians -- who earn an average of $2,000 monthly -- maintain the miles of conveyor belts and technically complex chemical ore separation plants. They eat for the same low prices in a company-run cafeteria.

Just outside the cafeteria is a sandbagged machinegun emplacement where two soldiers dozed in the noon heat one recent day. A small tank rumbled around the shady, tree-lined streets of the European section.

"That's for security," one Zairian government official said. "So the whites will feel safe."

About 450 European technicians fled Kolwezi last year after invading Shaba tribesmen, driven from the province into Angola in the early 1960s, were repulsed by French Troops. Western observers predicted that, unless the Europeans returned, Kolwezi's mining operations would barely run.

But the Zairians brought production up to near capacity of both cobalt and copper. Meanwhile, the technicians have been trickling back, and now number a little more than 200.

For Zairians working in Kolwezi, their initial success and the memory that the French troops came to rescue the Europeans have left a bitter aftertaste, according to one Zairian who declined to be identified.

"We feel we could have run it by ourselves, but now the government has invited them back and we're being pushed out of the jobs reserved for the whites," he said.

"There is a lot of tension in Kolwezi," a Western source said. Thirteen years after Zaire nationalized the mines, he said, "decolonization has not been completed."

Zaire does not have enough technicians to run its mining operations without outside help for long periods, he said, "but the ones they do have feel they are not moving up fast enough."

"Gecamines was forced to re-recruit a lot [of Europeans] who had left, then bump the Zairians who had occupied their posts," he continued. "The Zairians also resent the high salaries of the Europeans, but on the other hand" there are 150 close associates of President Mobutu Sese Seko on Gecamines' payroll "drawing high salaries and doing absolutely nothing."

Last year's attack on Kolwezi was the second invasion of Shaba Province (formerly known as Katanga) in two years. While the rebel's initial aim, during the early 1960s when they were driven into Angola, was secession, their announced objective in the recent attacks was to topple Mobutu's government by cutting off its major source of revenue.

After the French recaptured the city, a 2,500 inter-African force stayed here until last August to protect the mining industry.

Foreign observers question whether the generally undisciplined Zairian Army could repulse a third attack. Recruited from everywhere but Shaba Province, the Army is looked upon here as an occupation force.

Except for a 4,200 paratroop and infantry force recently trained by the French and Belgians, sources said, most of the troops are corrupt. In the past, Army officers have pocketed their soldiers' pay and diverted their food from the mess hall to sell on the black market, they said. The soldiers have habitually extorted money from Shaba residents and are suspected of engaging in armed holdups while dressed in civilian clothes.

Gecamines, as the foundation of copper-cobalt mining, keeps 40 percent of the foreign exchange it generates to import essential machinery and food for its 36,000 emplayes.

"But an unknown amount of that is siphoned off" by Mobutu's close circle of advisors, one knowledgeable source said.

"I know it's ridiculous," he added. It's like killing the only goose that's laying any eggs."