Di­a­mond is the hard­est ma­te­rial

Di­a­monds are much harder than steel and gran­ite, but they are not na­ture’s most ro­bust ma­te­rial.

Science Illustrated - - MYTHS -

Di­a­mond has long been known to be the world’s hard­est ma­te­rial, but the sparkling min­eral is now only No. 4 or per­haps ranks even lower. In 2005, Ger­man sci­en­tists pro­duced a much harder ma­te­rial con­sist­ing of densely packed, tiny car­bon rods. Four years later,

HARD MA­TE­RI­ALS PACK ATOMS DENSELY

The dif­fer­ence be­tween di­a­mond and lons­daleite is solely in the shape of the crys­tals' 3D grid. Both ma­te­ri­als con­sist of car­bon, and all atoms have pow­er­ful bind­ings to their cloe­sest neigh­bours in the grid. Chi­nese sci­en­tists stud­ied two nat­u­ral min­er­als, wurtzite boron ni­tride and lons­daleite and cal­cu­lated that they were 1.18 and 1.58 times harder than di­a­mond, re­spec­tively.

Lons­daleite pri­mar­ily ex­ists in me­teor craters, as ex­treme pres­sure is re­quired to pro­duce the min­eral; a pres­sure that can only oc­cur by Earth’s sur­face in case of a me­teor strike.

Di­a­mond: The car­bon atoms are lo­cated in a pow­er­ful, cube-shaped crys­tal struc­ture. BIND­INGS ARE AN­GLED D I F F E R E N T LY. Lons­daleite: The car­bon atoms are lo­cated in lay­ers with a very pow­er­ful, hexag­o­nal, crys­tal struc­ture.

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