Calcite cannot be scratched by a fingernail but can be scratched by a copper penny.
• The resistance of a material to scratching is termed as hardness. It is the characteristic by which minerals can be classified in relation to a standard scale of 10 minerals called the Mohs scale of hardness.
• The hardness of a mineral can be predicted by seeing the comparative toughness or ease with which mineral is scratched by another tool.
• Several objects can be used for scratching like a copper coin, finger nail, window glass, the needle, and others.
• On the Mohs hardness scale, talc and gypsum comes at 1 and 2 position, which signifies that it can be scratched easily even with a finger nail.
• While calcite is an element, which cannot be scratched with a fingernail but can be scratched with the help of a copper penny. Calcite comes at 3 in the Mohs hardness scale.
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