seldseen
seldom seen, rare, uncommon
archaic
And seldseen costly stones of so great price.
Where it comes from
From Middle English seldscene, seltsene (“rarely encountered, seldom seen; rare; as adv. seldom, rarely”), from Old English seldsīene, seldsēne (“rare, extraordinary, unfamiliar, uncommon”). Cognate with Old High German seltsāni, Modern German seltsam.
Adapted from the Wiktionary entry seldseen (CC BY-SA 4.0).