Mohs scale Other hardness scales Cheese scale Commentary

Friedrich Mohs geology

Mohs scale

• Relative hardness of minerals
• is easy to determine with a scratch test,
• a means described by Theophrastus
• in his treatise On Stones around 300 BCE,
• but not formalized until 1812
• when Friedrich Mohs proposed
• a non-linear ordinal scale
• of mineral hardness
• from 1, represented by talc,
• to 10, represented by diamond.

Other hardness scales

• Thomas Turner
• and his sclerometer, 1896,
• Johan August Brinell
• and his ball indentation tester, 1900,
• Gabriel Janka
• and his ball hardness test for wood, 1906,
• Eugene Meyer
• and his indentation tester, 1908,
• Paul Ludwik
• and his differential depth hardness measurement, 1908,
• Hugh M. Rockwell and Stanley P. Rockwell
• using Ludwik’s method, 1914,
• Albert Ferdinand Shore
• and his durometer in the 1920s,
• Raymond R. Ridgway
• and his extension of Mohs scale, 1933,
• Charles E. Wooddell
• and his wear-resistance scale, 1935,
• Robert L. Smith and George E. Sandland at Vickers Ltd.
• and their pyramidal diamond indenter, 1921,
• Frederick Knoop
• and his microhardness tester, 1939,
• and Leeb and Brandestini
• and their rebound hardness test method, 1975,
• Ernst Schmidt
• and his hammer for testing concrete, 1975,
• König and Persoz
• and their pendulum testers for paint and other coatings
• introduced scales
• that were more linear
• and more useful to industry,
• but the Mohs scale
• remains a standard
• for field geologists.

Cheese scale

“How can you govern a country that has two hundred and forty-six varieties of cheese?” —Charles de Gaulle

• A good science project
• might be to evaluate
• the relative hardness of cheeses.
• Industry terms such as
• “fresh soft” and “fresh firm”
• “semi-soft” and “semi-hard”
• are woefully unscientific.
• Parmesan, cojita, and aged gouda
• are harder than cheddar,
• but how hard is dry jack?
• Is cheddar harder than blue?
• Is Swiss harder than Gruyère?
• Is goat harder than sheep?
• How does hardness
• affect melting temperature?
• Does Stilton have a standard hardness?
• Does hardness correlate
• with reduced moisture content?
• And what about fat?
• Many questions remain
• and I won’t do the research
• because I’m allergic to cheese.