Not gold, silver or uranium, but the mining of human memory. It is more valuable than going after ore because it’s treasure that rarely gets spent. That is unless someone who has important history to tell - say a World War II soldier, or a survivor of the atomic bombs dropped on Japan - dies before their memories can be documented.

The new documentary by Steven Okazaki, “White Light, Black Rain: The Destruction of Hiroshima and Nagasaki,” arrives in time with many survivors of the atomic attack just barely still around to tell their stories. Okazaki met with 500 survivors starting back in 1980. In the following decades he sat down and interviewed 100 of them. Eventually that group was narrowed down to the 14 survivors who appear in the film.

Historians and other armchair experts are given no screen time. Consequently the film has a lasting and meaningful impact because we learn story after story of personal horror weighted with actual human emotion. But in some cases, it’s just as powerful that those horror stories come with a lack of emotion, like the interviews of members of the American Air Force crew that dropped the bombs on Aug. 6, 1945.
There’s a similar formula in Ken Burns’ upcoming 14-hour documentary about WWII called “The War.” His crew interviewed 500 American WWII vets from four towns in America. The stories of 40 veterans from Connecticut, Alabama, California and Minnesota made the final cut.

Tapping directly into human memory is an affective way to tell a story. Burns, however, in a recent column for USA TODAY Weekend magazine, said he recognizes the pitfalls of such a research method.

“Memory can be flawed,” Burns writes. “It can be incomplete. It can lend itself to exaggeration and hyperbole. It can be entirely incorrect. So that’s why we always say ‘Trust, but verify.’ For my documentary we used available military records, for example, to authenticate memories of battle and resulting injuries.”

“The War” is set for broadcast on PBS in seven installments over two weeks starting Sept. 23. “White Light, Black Rain” is now airing on HBO.