Alfred Harker FRS[1] (19 February 1859 – 28 July 1939) was an English geologist who specialised in petrology and interpretive petrography.

A geological tour of Western Europe in 1887 introduced him to the metamorphic rocks of the Ardennes which proved to be an influential experience to his continuing research.

Harker accompanied Professor Thomas McKenny Hughes to the United States in 1891 where they attended the 5th International Geological Congress.

Harker's active fieldwork programme also saw him collaborating with Professor John Edward Marr of the Department of Geology on the volcanic rocks of the Lake District in 1889.

The Sedgwick Museum of Earth Sciences opened in 1904 and three years later, Harker published research on material he had prepared petrological rock slices of.

After his retirement, he was given the post of honorary curator of the Cambridge Petrological Museum, and their extensive rock collection bears his name.

[9] The archive comprises notebooks, sketchbooks, and photograph albums detailing geological excursions in the U.K from the late nineteenth century.