Sinyushka's Well — Russian fairy tale character

"Sinyushka's Well" , also known as "The Blue Crone's Spring" and "The Blue Baba of the Marsh", is a folk tale (the so-called skaz) of the Ural region of Siberia collected and reworked by Pavel Bazhov. It was first published in the Moscow Almanac in 1939. It was later included in The Malachite Casket collection. "Sinyushka's Well" is one of the most famous stories in the collection and is still popular nowadays.
It is one of the tales about mining pioneers. The tale is told from the point of view of the imaginary Old Man Slyshko.
There is a blue fog above Sinyushka's well. Her main function is to keep the mountain riches from the greedy and undeserving.