'1 of the 3 minerals on the Mohs scale that can be scratched with a copper penny'
Calcite, gypsum or talc
GEOLOGY: 1 of the 3 minerals on the Mohs scale that can be scratched with a copper penny
1 of the 3 minerals on the Mohs scale that can be scratched with a copper penny
1 of the 3 minerals on the Mohs scale that can be scratched with a copper penny
GEOLOGY
Calcite, gypsum or talc
GEOLOGY