The Properties of graphite and diamond

	Graphite	Diamond
Appearance	Black soft solid	White / colourless when pure. When cut they are clear and sparkle. Impure diamonds may have slight colour.
Electrical conductivity	For a non metal graphite is a very good conductor indeed	Diamond has a very low electrical conductivity
Thermal conductivity	The thermal conductivity of graphite is quite low	The thermal conductivity of diamond is VERY high
Hardness	Graphite is extremely soft	Diamond is the hardest natural substance known to man
Enthalpy of formation (KJMol^-1)	0	+1.895
Density (g cm^-3)	2.260	3.513
Melting point (K) 1ATM	At 3700K it sublimes and decomposes	No data for diamond

From above it is easy to see that there are many differences in these two allotropes I would have put in the data for buckminsterfullerene if I could find any.

Below is a phase diagram for carbon at various pressures, this was take from the University Of Bristol's Chemistry Deparments CVD diamond research group's website.

From the picture above it can be seen that liquid carbon can exist at extreme pressures and temperatures, but it does not exist at 1ATM, the solid just sublimes.

Go to the carbon home page