During the mid-23rd century, the Tellarites employed Tellarite ships for questionable, possibly illegal mining operations, on the planet Coridan.

Prior to the Babel Conference in 2268, Vulcan Ambassador Sarek revealed to Tellarite Ambassador Gav his interest in supporting Coridan's admission into the Federation.

Sarek noted that that planet had a nearly unlimited wealth of dilithium crystals, but was underpopulated and unprotected, which invited illegal mining operations, which he implied the Tellarites were involved in, by referring to how some Tellarite ships have been observed carrying Coridan dilithium crystals from the planet. (TOS: "Journey to Babel")