He was a professor of mineralogy and economic geology at Northwestern University from 1893 to 1906, when he was named Illinois State Geologist.
[1] Crook taught at Northwestern until September 15, 1906, when he was named Illinois State Geologist by Charles S. Deneen.
Crook greatly expanded the museum, moving it to the Centrannial Building on the Illinois State Fairgrounds.
Crook wrote The Guide to Mineral Collection, which was a popular text in colleges in museums.
[1] He was buried there in Roselawn Memorial Park, though a marker for him is instead found in Oak Ridge Cemetery.