Hard Red Mineral With Pointy Crystals
Puzzle 3 of Spy World Medium Pack
Question is: Hard Red Mineral With Pointy Crystals
and the answer is: SPINEL
Word Meaning:
SPINEL — (mineralogy) Any of several hard minerals of cubic symmetry that are mixed oxides of magnesium and aluminium and are used as gemstones of various colours.
Definitions from Wiktionary.