Which mineral is harder than calcite but wont scratch a knife?

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Hardness is a measure of a mineral's resistant to abrasion. This property is easily determined and is used widely for field identification of minerals. More than a century ago. Friedrich Mohs (1773-1839), a German mineralogist, assigned arbitrary relative numbers to ten common minerals in order of their hardness.

Hardness
Mineral
Test
1TalcFingernail (2.5)
2Gypsum
3CalciteCooper coin (3)
4FlouriteKnife blade (5.5)
5Apatite
Glass plate (5.5+)

6K-feldspar
7QuartzStreak plate (7)
8Topaz
9Corundum
10Diamond
A simpler version of the Mho's scale can be established using three types of hardness:

SOFT - Minerals that can be scratched with a fingernail

INTERMEDIATE - Minerals that cannot be scratched with a fingernail but can be scratched with a steel nail.

HARD - Minerals that cannot be scratched with a steel nail.

Mineral
Hardness
Calcite

INTERMEDIATE

Mineral cannot be scratched with a fingernail but can be scratched with a steel nail.

Gypsum

SOFT

Mineral can be scratched with a fingernail

Pink Feldspar

HARD

Mineral cannot be scratched with a steel nail.

White Feldspar

HARD

Mineral cannot be scratched with a steel nail.

Gray Feldspar

HARD

Mineral cannot be scratched with a steel nail.

Quartz

HARD

Mineral cannot be scratched with a steel nail.

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