A stunning array of items belonging to Georgia O’Keeffe and Alfred Stieglitz, the husband-and-wife duo who defined an era in the history of American art, will be auctioned off at Sotheby’s on March 5.

The wide-ranging collection of artworks and objects include unseen items and personal effect owned by the couple throughout their life together. The items come to auction as part of the collection of the artist Juan Hamilton, a friend of O’Keeffe’s.

Included in the sale is an abstract painting by O’Keeffe that Hamilton inspired. Titled From a Day with Juan (1977), it carries an estimate of $1.2 million to $1.8 million. Also on sale will be O’Keeffe’s famous painting Nature Forms–Gaspé (1932), which has an estimate of $4 million to $6 million; a rare and (probably) never-before-seen example of her stoneware pottery, estimated to go for between $10,000 and $15,000; and works on paper with an upper estimate of $120,000.

Alfred Stieglitz, Georgia O’Keeffe – Hand and Wheel (1933). Image courtesy of Sotheby’s New York

“The selection speaks to the meaningful personal and professional relationship that O’Keeffe had with Alfred Stieglitz, the changing face of the New York art scene, as well as the evolving times in America,” Kayla Carlsen, Sotheby’s head of American art, said in a statement issued to Artnet News.

Carlsen says Stieglitz’s Georgia O’Keeffe – Hand and Wheel (1933) in particular “is a perfect example of these overlapping narratives. Not only is the work stylistically progressive, but the subject depicts O’Keeffe’s hand on the wheel of her new vehicle, about to embark on a southwestern-bound trip leaving her husband Stieglitz behind in New York—a progressive endeavor for the time.”

The photograph—one of only three known prints of the shot, and the last one in private hands—carries an estimate of $300,000 to $500,000.

Pigments belonging to Georgia O’Keeffe, labelled by the artist. Image courtesy of Sotheby’s New York.

Works by Hamilton and members of the Stieglitz Circle who exhibited at his famous 291 art gallery in New York during the 1910s will also be on offer.

In addition to these artworks are ephemera such as O’Keeffe’s and Stieglitz’s marriage certificate and a 1962 edition of Ulysses by James Joyce, signed by the painter Marsden Hartley. There are also examples of writings by O’Keeffe and pigments she used to paint.

A public preview of the items opens at Sotheby’s New York on February 26.