Hardest Known Natural Material
This page is the CodyCross answer for the clue below from Circus, Group 99, Puzzle 4 (Downtown Wagon).
Question is: Hardest Known Natural Material
and the answer is: DIAMOND
Word Meaning:
DIAMOND — (uncountable) A glimmering glass-like mineral that is an allotrope of carbon in which each atom is surrounded by four others in the form of a tetrahedron.
Definitions from Wiktionary.