"a locus of" is correct and usable in written English.
You can use it to refer to the position, place, or center of something. For example, you could say "She was a locus of power in the organization."
For one character, Paris is "a locus of several desires".
The bursting housing bubble remains a locus of concern.
Robin Hood's Sherwood is a locus of freedom from tyranny.
The Middle East will remain a locus of enormous diplomatic attention.
Until then, whales had been a locus of fearful wonder, or an industrial resource.
Sri Lanka is a locus of guerrilla war and arms smuggling.
Legends on the Net: An Examination of Computer-Mediated Communication as a Locus of Oral Culture.
The group residence on Capitol Hill, owned by Mr. Miller, has a reputation as a locus of Democratic power.
In the years since, the Horn of Africa, and Kenya in particular, has become a locus of U.S. counterterrorism.
Isegawa makes his country a locus of life, tragedy and character that, however roughly scrawled, stays with us.
Hudson Valley Hospital Center, formerly Peekskill Hospital, has long been a locus of relationships among northern Westchester's influential Republicans.
