Crossword clue: a cavity in a rock, having its interior surface studded with crystals and sometimes filled with water; a geode.
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
an adherent of an esoteric monotheistic religious sect living in the relative security of the mountains of Syria and Leb