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Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray Group 2 alkaline earth metal, fifth-most-abundant element by mass in the Earth's crust.
C 1340 (OTTO) Calcium, granular, 99% Cas 7440-70-2 - used to Precursor to Ca8Al3 and Ca13Al14; intermetallics with new metallic Zintl phases