Graphite

Graphiteone ofallotropescarbon. Unlike diamond, graphite isconductor,can be used,instance, asmaterial inelectrodesan electrical arc lamp.

The pi orbital electrons delocalized acrosshexagonal atomic sheetscarbon contributegraphite's conductivity. In an oriented piecegraphite, conductivity parallelthese sheetsgreater than that perpendicularthese sheets.

The loose coupling amongsheetsgraphite contributesanother industrially important property -- graphite powderused asdry lubricant. Graphitealso usedpencils.

Physical characteristics

• Colorblack silver.
• Lustermetallicdull.
• Transparency crystalsopaque
• Crystal systemhexagonal; 6/m 2/m 2/m
• Crystal habits include massive lamellar veinsearthy masses,scaly granulesmetamorphic rocks.
• Hardness1 - 2
• Specific gravity2.2
• Cleavageperfectone direction.
• Fractureflaky.
• Streakblack graybrownish gray.

Associated minerals include quartz, calcite, micas, iron meteoritestourmalines.

Other characteristics: thin flakesflexible but inelastic, mineral can leave black marks on handspaper, conducts electricity.

Notable occurrences include New YorkTexas, USA; Russia; Mexico; GreenlandIndia.

Best field indicatorssoftness, luster, densitystreak.

• Diamondhardest mineral knownman, but graphiteone ofsoftest.
• Diamondan excellent electrical insulator, but graphite isconductorelectricity.
• Diamond isultimate abrasive, but graphite isvery good lubricant.
• Diamondusually transparent, but graphiteopaque.
• Diamond crystallizes inisometric system but graphite crystallizes inhexagonal system.

External link

• The Graphite Page