There are a lot of possible answers for this questions. The calcite that composes the Redwall limestone can be distinguished from the quartz that composes the Tapeats sandstone: (1) Calcite bubbles with acid. (2) Calcite shows cleavage. (3) Quartz is harder than calcite. (4) Calcite is composed of calcium (Ca), oxygen (O), and carbon (C), and quartz is composed of silicon (Si) and oxygen (O).