A Mineral Yielding Silver
Puzzle 15 of Making Sushi Pack
Question is: A Mineral Yielding Silver
and the answer is: ARGENTITE
Word Meaning:
ARGENTITE — (mineralogy) Silver sulfide (chemical formula Ag₂S), a primary ore of silver, in cubic or hexoctahedral crystals.
Definition source: Wiktionary (CC BY-SA 4.0)