April 15 marks the 100th anniversary of the sinking of the Titanic. A chilling reminder of the tragedy will go on the auction block a few days later -- a rare photo said to capture the iceberg that sank the supposedly unsinkable ship.

The black and white picture was taken by a passenger on the RMS Carpathia, the ship that rescued 705 survivors of the April 15, 1912, sinking, according to RRAuction, which is selling the photo and other Titanic artifacts online from April 19 to April 26. Also visible in the image is the hull of what the auctioneer said is a Titanic lifeboat that had saved lucky survivors from the icy Atlantic. Auction company vice president Bobby Livingston said the black and white iceberg photo has an estimated value of $5,000 to $8,000.

"It has impeccable provenance," Livingston told HuffPost. "It came from the estate of John Pillsbury Snyder, who survived the Titanic. All of his memorabilia was sold last year as one lot, including a letter written on Titanic letterhead and a letter from his brother saying how worried he was about him while trying to find out if he made it."

At the time of the voyage, Snyder was a 24-year-old Minnesota man returning from a two-month honeymoon tour of Europe with his new bride, Nelle. The couple was among 25 passengers heading for Minnesota and among the few who had experienced the ship's luxurious first-class quarters.

The photo itself was taken by Mabel Fenwick, a newlywed passenger on the Carpathia who struck up a friendship with the Snyders.

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PHOTO GALLERY

As you might expect, the photo of the iceberg is getting a titanic amount of interest. An expert said it needs thorough study before it can be determined authentic.

Photo analyst Marc Dantonio said the picture quality resembles photos he owns that were taken during the same decade as the Titanic tragedy and it was definitely taken from a ship that steaming away from an iceberg.

"But I would need to see a photo of the Carpathia and need to see the lifeboat structure before I could determine if the photo was taken on the ship," Dantonio said.