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Specific gravity 2.3, Moh hardness 1.5  Occurs naturally in places like Ceylon and Mexico.  Also produced synthetically.  The Acheson process heats a mixture of anthracite or coke dust with sand to a white heat for 24 hours.  The combination of silica in the sand with the carbon can form abrasive silicon carbide.  Beware of synthetic graphite contaminated this way.  Beware of high ash contents in some natural graphites.  Get into the habit of checking graphite ash for abrasiveness.

Chemically, graphite is very un-reactive.  It is soft, crystalline, dark grey in color, and greasy to the feel.  In burns in air at 700°C (1300°F).

A medium (200/250°C) temperature lubricant.  Reduces friction level, but may increase fade.

Graphite possesses lower mu when wet, as in humid conditions.  Has been suggested as an effective cure for EMS (Early morning sharpness).

With graphites it is important to know exactly what is being bought.  Carbon block and coke (amorphous carbons) have the same atomic arrangement as graphite, but are generally regarded as impure forms.  These are materials being marketed as graphite which are often not much different from calcined petroleum coke.  (Calcined petroleum coke is 98-99% fixed carbon).  Many are blends of graphite and coke.  They may look like graphite.  They may have the correct ash content, but they will not behave like graphite.  A quick check for graphite is to rub it between finger and thumb.  Graphite will feel lubricious and will leave a graphite sheen.  Coke will not.  Try it and see for yourself.  This test can also give an indication of the degree of lubricity.