thermal conductivity

Material class	$\lambda$ in W(m K)
Gases at 1 bar	0.007 - 0.17
Air	0.026
Insulation materials	0.02 - 0.20
Non-metallic liquids	0.08 - 0.70
Non-metallic solids (stone, concrete)	0.03 - 2.1
Wasser	0.6
Liquid metals	8 - 70
Alloys	13 - 120
Pure metals	50 - 400
Copper	399

Isotrope