To determine which mineral could be scratched by a penny but not by a fingernail based on the Mohs Hardness Scale, we need to consider the hardness values:
- Fingernail: ~2.5
- Penny (made primarily of copper): ~3.0
Now, we analyze the hardness of the minerals given in the options:
A) Talc - Hardness 1 (can be easily scratched by a fingernail) B) Gypsum - Hardness 2 (can be scratched by a fingernail) C) Calcite - Hardness 3 (can be scratched by a penny) D) Fluorite - Hardness 4 (cannot be scratched by a penny)
From this information, the mineral that can be scratched by a penny (hardness 3) but not by a fingernail (hardness 2.5) is:
C) Calcite