Graphite crystals can be used as a lubricant.
true
false

I think its true because they are a soft solid that can be broken down into a liquid... Hope this helps in any way :3

 Graphite and Diamond are allotropes of Carbon meaning they have the same chemical properties of carbon (they both burn, yes diamond burns. At 1500 Celcius), but totally different physical properties. Graphite is a good conductor of both electricity and heat, Diamond isn't. Graphite is slippery, Diamond isn't. Graphite is soft, diamond is hard. Diamond is transparent, graphite is a black powder. 

The reason for this is that the lattice structure( geometrical arrangement of carbon atoms in the crystal) of G and D are vastly different (hence different physical propetries), but they are basically the same element(hence the same chemical properties.) 

Graphite has what is known as a Hexagonal Lattice Structure. Imagine a thin slice of a honeycomb placed at a certain distance over another slice, which in turn is placed over the next and so on, with each vertex of each hexagon representing a carbon atom. This is what the graphite crystal structure looks like. Now, the layers of the lattice are bound to the adjacent layers by weak Van der Waals bonds, which allow the layers to slide over one another easily, like a teetering pile of paper sheets. Hence you get the quintessential properties of Graphite - softness, slipperiness and hence it makes an excellent solid lubricant. 

Diamond, on the other hand has a tetrahedral "diamond" structure, in which carbon atoms are held rigidly by neighbouring atoms by powerful bonds that require a great deal of force to be broken. Hence Diamond is hard, strong and can be used as an abrasive to grind and polish other materials 

So to answer your question its True