Antimony is a chemical element with symbol Sb (from Latin: stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name, kohl.
Explanation: The reason for this is because calcite has a hardness of 9 while feldspar has a hardness of 21. Calcite can scratch Gypsum which has a hardness of 3.
