The phrase "rarely known" is grammatically correct and can be used in written English.
Example: The history of this ancient civilization is rarely known to the general public.
Italian governments are rarely known for efficiency.
National laws are rarely known, let alone enforced, in rural Africa.
Moses, of course, was rarely known to let sentiment stand in the way of cold pragmatism.
Death is a secretive business these days, so the manner of departing is rarely known by most.
Still, most poets don't travel well; apart from an oddity like Seamus Heaney or Derek Walcott, poets are rarely known outside their home countries (worse, they're rarely known outside their hometowns).
They note that the benefactors are rarely known, but priests at nearby parishes often perform services in them.
Congress — rarely known for its subtlety on such matters — is working on its own, even tougher sanctions legislation.
Oddly for such a media-reliant industry, the stars of the show are rarely known for being articulate public speakers or great thinkers.
Photograph: Dan Chung Often asked what foreign food trend will next influence fusion-minded New York chefs, I have rarely known what to guess.
The names of the architects and master craftsmen behind such masterpieces as the Red Fort in Old Delhi are rarely known.
The Japanese Parliament, rarely known for quick action, is rushing to approve a bill for financial aid for the returned kidnapping victims.
