DENSELY PACKED with information, The Randlords, despite its intrinsically dramatic subject matter, is sometimes hard going. Yet this timely story, of the mining kings of South Africa, is well worth the concentration that it takes to follow the complex scheming of its unheroic heroes. We Americans debate apartheid in an information vacuum. Wheatcroft shows us that it is only one aspect of the history of a young and divided country, hammered out of a frontier background in a relatively few years of violence and greed.

Gold and diamonds, and the lusts they awaken, shape the tale. Around 1860 -- not long ago in historical time -- South Africa was a relatively poor land, with few enticements for seekers of quick and easy fortune. The region around the Cape of Good Hope had been settled two centuries earlier by Dutch farmers, the celebrated Boers (or Afrikaners, as they later styled themselves). They were stubborn, independent, hardworking and heathen-hating Calvinists, and when Great Britain won the "Cape Colony" from The Netherlands in 1814, they had trekked far inland to raise grain and cattle in isolation from London's worldly reach. Left to themselves by an easygoing British African policy, they beat down the local blacks and set up quasi-independent republics.

But in the 1870s and 1880s, the discovery of gold and diamond mines in the Transvaal and the Orange Free State ended this conservative idyll. Prospectors flocked to Kimberley, Bloemfontein, Johannesburg and Pretoria, which became swaggering boom towns full of mud, sin, adventure and overnight fortunes. The big money fell to the arriviste numbers of Wheatcroft's cast, who multiplied modest stakes into millions in sterling by shrewdly buying and selling shares in the mines, and later warring or combining to control prices and output of the glittering end-products. The Randlords' names (except possibly for that of Cecil Rhodes) are generally unfamiliar to American readers. Few of us have heard of Barney Barnato, J.B. Robinson, Alfred Beit, Abe Bailey, Hermann Eckstein, or Ernest Oppenheimer, but they were the counterparts of our Hearsts and Guggenheims, bred in the same grabby heyday of expansion and conquest.

South African history, however, had its special corrugations. To solve a labor shortage in the mines, the Randlords brought in thousands of blacks, who lived and worked under brutal and humiliating conditions that amounted to imprisonment. Yet the mere act of their transplantation shook up patterns of tribal life more decisively than dynamite and Bibles. South Africa could never again be the same. The Afrikaner rulers knew that, too. Their control of mining lands and concessions brought them fabulous prosperity, but along with it came a sea of blacks, of Asian laborers and shopkeepers, and of still other "Uitlanders" (foreigners) from Britain and Europe, with powerful connections. Ultimately, their power was bound to be diluted, and their exclusive control weakened over the land that they devoutly believed was theirs by right of pioneering struggle.

So it happened, in fact. The Boer War of 1899 to 1902 subdued the republics, which, in 1910, were merged into a Union of South Africa. A modern, scientific imperialism of mines and roads and rails and refineries required more than forts and trading posts. It had to penetrate and subjugate pre-existing local societies and governments -- those of the Boers no less than of "native" black kingdoms that were changed from protectorates into colonies.

THAT WAS what the Randlords wrought. The stream runs onward. South Africa became, in time, a dominion and then -- only in 1961 -- an independent nation. Its current struggles replay old themes of conflict among the groups brought into contact by the great mining boom: blacks, "coloreds," white business liberals (descendants of the Uitlanders) and Afrikaners aflame with ancestral certainties. For these last, whose political vehicle is the Nationalist party, apartheid is a doctrinaire, and ultimately doomed attempt to hold back the tide of modernization that is floating black Africa into the mainstream of struggle for independence. South Africa's underground wealth calls the figure for all the dancers. It creates the cities in which African workers learn to visualize a new world, opens the gates to the worldwide contacts which sustain the moderates, and buys the guns and technology for Nationalist resistance.

Wheatcroft does not dwell on such political matters, nor does he moralize, though his moral is clear enough. He excels, instead, in revealing sketches of the Randlords and some of the byproducts of their success. It is interesting to learn, for example, that the prominence of Jews among the diamond-and-gold aristocracy made capital for the turn-of-the-century anti-Semitism of both right and left (the Jew was condemned either as an outsider or a plutocrat) that grew to such tragic dimensions. Wheatcroft also demonstrates that the eccentricities and tragedies of the newly rich and their children make for colorful reading in any country. He also whets my appetite, at least, to learn more about the strange career of Cecil Rhodes, that peculiar amalgam of fantasist, organizer, racist and visionary who is a true scoundrel-saint of late 19th-century Western society, so triumphantly busy in its brief authority.

The Randlords is most accessible to those who have some prior acquaintance with modern Britain. But for any reader, it is a valuable glimpse into the eventful and complicated background of the moral questions that haunt our era. Sweet are the uses of history, which leaves us to struggle for answers, but arms us with perspective.