Moh's Scale of Hardness
From one to ten based on a series of 10 minerals, each of which will scratch the one before it

Samples. Source: Wikipedia

Talc, the softest; used for dusting punctures
And so-delicate baby bums, then
Gypsum, scratched by calcite, scored by fluorite,
Which defers to apatite,
[Called in Greek deceit for basely
Simulating others.]

The next one up is orthoclase
[Gk: a fracture of the true].
It submits to quartz's tips
Incised by topaz gem which then
Corundum dominates.

And ultimate and at the top,
The shining adamantine prize:
The boss: diamond, rough, untouched
And cut by none except by kin.

So do we just score and scratch
Until we find an equal then we
Finely grind and pulverize each other down.

Clive Donovan

If you have any thoughts on this poem,  Clive Donovan  
would be pleased to hear them.