America's oldest and poorest landowners suddenly are talking and acting very much like businessmen.

Indians -- particularly the $250,000 whose tribes are members of the Council of Energy Resource Tribes (CERT) -- sit on top of vast portions of the nation's energy reserves, and, as the drive for American energy independence assumes mounting urgency, they see unprecedented possibilities for bettering their economic lot.

But eager as many of the 25 CERT tribes are to exploit the resources on reservations that dot the western landscape, they are even more anxious to ensure they don't become exploited themselves.

"We feel enough has been taken from us. We want the right to manage what's left," said Dick Monteau, an official in southeastern Montana's 3,200 member Northern Cheyenne tribe.

There are an estimated 23 billion tons of recoverable coal on his tribe's 44,000 acres, but Monteau said the Northern Cheyenne fell victim in the past to numerous "bad leases" that have worked to the tribe's detriment. Because of that, the Northern Cheyenne now oppose energy resource development altogether.

The other CERT tribes, however, favor it and have taken ambitious steps toward making their mineral wealth work for them.

Last week, the council hired Ahmed Kooros, an American-educated Iranian who had served as deputy economics and oil minister in Iran, to be the council's chief economist. Also last week, CERT officials met in Denver with incoming Energy Secretary Charles Duncan. During the 45-minute session, Duncan pledged to work closely with the tribes in developing energy on their land.

Reserves lying under Indian land include: possibly as much as 50 percent of the known reserves of uranium in the nation; 15 percent of all the nation's coal and 33 percent of its low-sulfur coal; between 3 and 4 percent of the country's oil and natural gas, and significant amounts of geothermal energy.

Ed Gabriel, a non-Indian and former Department of Energy official who is executive director of CERT in Washington, contends that Indian lands can provide between 1.5 million and 4 million barrels of fuel pad day by 1990. Under President Carter's energy plan, the synthetic fuel output by 1990 was projected at 2.5 million barrels a day.

CERT officials believe their lands' fuel potential could be reached within a decade if the federal government would put up $600 million to get it started.

The initial federal investment -- less than one half of 1 percent of Carter's projected $142 billion program -- would be used for inventories, engineering studies, front-end financing, educational programs to train Indians for technical jobs and future CERT needs.

Full development, Gabriel anticipated, would be done from private capital attracted to the potential of native American resources.

Skepticism still has a foothold in some Indian quarters, however.

In an as yet unanswered letter to the president, Peter MacDonald, CERT's chairman and leader of the 150,000 member Navajo tribe, the nation's largest, wrote that by failing to consult Indians before announcing his energy program, Carter "appeared to look upon these native Americans . . . as foreigners."

After last week's meeting with Duncan, MacDonald appeared pleased, but nonetheless retained some doubts.

But the predominant tone favors careful but rapid development, with Indians charting their own course and being at least the equals of other energy interests looking to take resources out of the ground and put them to work.

"The tribes are going to be more willing than the corporations to lose that extra dollar profit rather than harm their environment," Gabriel said. "They are not going to have happen what happened in the past, have the land torn up and desecrated," he added.

Fears that Indians will band together to form a kind of domestic oil cartel are pooh-poohed by both Indian leaders and government officials.

"This is an opportunity for CERT tribes to work very closely with their government and get the kind of assistance they should have gotten a hundred years ago," said Floyd Correa, governor of the Laguna tribe in west central New Mexico, on whose land sits Anaconda Corporation's huge uranium mine.

An Energy Department spokesman also sees little risk that Indians would export resources, saying, "From an economic standpoint such resources would be best utilized in the United States."

Indian leaders see this "tremendous potential wealth" as Gabriel puts it, helping in the long term to build up what are now weak or substandard schools, highways and other facilities. A recent University of California study showed that Indians make only 60 percent of the national average income, and Gabriel estimated the per capita income for Indians at $1,500 per year.

If all that is hoped for comes about, Gabriel said, "it is a success story for America . . . It's telling the American consumer, 'We've got a sub-group we've been battering around. Now they are going to lead the way.'"