Author Mark Twain, born Samuel Langhorne Clemens, is shown in this undated portrait released by The Mark Twain House & Museum. (The Mark Twain House & Museum/Associated Press)

A 64-page handwritten tribute by Mark Twain to his daughter after she died at age 24 has sold at Sotheby's in New York for $242,500 US, almost doubling pre-sale estimates.

It was the highlight of the Mark Twain Collection of almost 200 letters, manuscripts and photographs that fetched $936,012 US at auction on Thursday.

The U.S. author, whose real name was Samuel Langhorne Clemens, wrote A Family Sketch shortly after the 1896 death of Olivia (Susy) Clemens from spinal meningitis.

"She was a magazine of feelings" of "all shades of force," he wrote of the daughter who had inspired some of his stories and who wrote her own biography of her father.

In the unpublished document, Twain also reminisced about his own childhood. It's been described as the missing chapter of his autobiography.

"What initially began as a tribute to his late — and undisputed favourite — daughter Susy thus devolved into a narrative that encompasses the whole of this family and friends as well as glimpses of incidents of his own childhood," auction house Sotheby's said in a statement.

Before the sale, University of California Twain expert Robert Hirst said any collector of the writer's works would be "willing to go hungry for two or three years in order to be able to buy it."

In November, the university will publish the first of three volumes of Twain's unabridged autobiography to mark the centenary of the writer's death and 175th anniversary of his birth.

Twain, who died in 1910 at the age of 74, was the author of American classics The Adventures of Tom Sawyer and The Adventures of Huckleberry Finn.

He spent his last few years recording his life, but left instructions that the works appear no sooner than 100 years after his death.