The Hardness of Selected Elements

Element	Hardness on Mohs scale
Caesium	0.2
Rubidium	0.3
Potassium	0.4
Sodium	0.5
Carbon graphite	0.5
White phosphorus	0.5
Lithium	0.6
Indium	1.2
Thallium	1.2
Barium	1.25
Strontium	1.5
Mercury	1.5
Gallium	1.5
Tin	1.5
Lead	1.5
Calcium	1.75
Cadmium	2.0
Sulfur	2.0
Selenium	2.0
Bismuth	2.3
Tellurium	2.3
Magnesium	2.5
Cerium	2.5
Lanthanum	2.5
Silver	2.5
Gold	2.5
Zinc	2.5
Aluminium	2.8
Copper	3.0
Antimony	3.2
Platinum	3.5
Arsenic	3.5
Iron	4.0
Nickel	4.0
Palladium	4.8
Zirconium	5.0
Cobalt	5.0
Beryllium	5.5
Hafnium	5.5
Molybdenum	5.5
Uranium	6.0
Titanium	6.0
Niobium	6.0
Manganese	6.0
Rhodium	6.0
Germanium	6.0
Ruthenium	6.5
Tantalum	6.5
Ruthenium	6.5
Iridium	6.5
Vanadium	7.0
Rhenium	7.0
Osmium	7.0
Silicon	7.0
Tungsten	7.5
Chromium	8.5
Boron	9.3
Carbon diamond	10.0

This list was taken from various sources.