Where is marble on the hardness scale?

Marble ranges from 2-5 on Moh's scale.

add. There are several hardness scales other than Mohs, which is an arbitrary scale of hardness. .

There is a Janka scale for wood, but be careful of the units used.

There is a Rockwell scale for the Hardness of steel. This measurement leaves little mark (impression).

There is a Brinell hardness scale which forces a hard steel ball into the test piece. This method leaves an impression on the test piece, but can be calibrated for steel, wood, and other metals.

The Vickers Hardness test uses a diamond indenter, and is often used for hard materials such as case-hardened material.

[Rockwell, Brinell, and Vickers have tables of equivalence.]

And, last of all is a hardness test for paints and similar. This test, BS3900 - E19, ISO 15184, uses ordinary pencils of various hardness to determine the hardness of the paint film.