Build-Up of Chalky Calcium Carbonate
This page is the CodyCross answer for the clue below from Concert Hall, Group 585, Puzzle 4 (Ride of the Valkyries).
Question is: Build-Up of Chalky Calcium Carbonate
and the answer is: LIMESCALE
Word Meaning:
LIMESCALE — A white, chalky deposit of calcium carbonate found in kettles, washing machines etc., especially in a hard water area.
Definitions from Wiktionary.