It may be preferred over the Rockwell, Vickers, and Knoop indentation tests because they yield different values for different cleavage axes.  
It was revised in 1933 by Ridgeway, Ballard, and Bailey to include synthetic compounds.  Hodge and McKay used a microcharacter to show it was approximately logarithmic, although a recently published article by Broz, Cook, and Whitney seems to dispute that claim.  It may be preferred over the Rockwell, Vickers, and Knoop indentation tests because they yield different values for different cleavage axes.  Because of its nonproportionality, most everyday objects are given values to the nearest one-half; for instance, standard window glass is listed at 5.5.  FTP, identify this scale named after an Austrian geologist, which uses the scratch test to rank minerals' hardness on a scale of talc's one to diamond's ten.
It was revised in 1933 by Ridgeway, Ballard, and Bailey to include synthetic compounds.  
{Mohs} hardness scale