Deep Blue Copper Carbonate Mineral
Puzzle 17 of Treasure Hunt Pack
Question is: Deep Blue Copper Carbonate Mineral
and the answer is: AZURITE
Word Meaning:
AZURITE — (mineralogy) A blue vitreous mineral; a basic hydrated copper carbonate, with the chemical formula Cu²⁺₃(CO₃)₂(OH)₂, used since antiquity as a blue pigment or ores to extract metallic copper.
Definitions from Wiktionary.