a person who studies and collects rocks for fun?: using a word with "rock"

Rock hound.

A person who studies and collects rocks for fun is commonly known as a "rockhound." The term "rockhound" combines the word "rock," referring to the object of interest, with "hound," which suggests a passionate pursuit or search. If you want to explore further, you can use online search engines or reference materials to gather more information about rockhounding, including recommended tools, techniques, and popular locations for finding rocks.