As some of you know, I originally trained and worked as a sort of geologist, specialising in cliff stability, foundations, and remediation of slope failures. But when I first started, I used to do a lot of field work which meant I used to wander around poking soil and whacking rocks.
It's pretty basic sometimes and some of the classifications we used hadn't changed for donkey's years. Geology isn't the fastest changing science after all.
For example, the Mohs scale of mineral hardness, devised by German mineralogist Frederich Mohs in 1812 (think of it as a geological overture), selected ten readily available minerals, and bunged them into a 'scale' of hardness.
It's not linear and somewhat arbitrary, but when a hammer is one of your finely tuned and calibrated pieces of equipment, then it's perhaps not that important.
So, Mr Mohs, how hard are you?
1 Talc, Talcum powder.
2 Gypsum. Plaster of paris. Gypsum is formed when seawater evaporates from the Earth's surface.
3 Calcite. Limestone and most shells contain calcite.
4 Fluorite. Fluorine from fluorite prevents tooth decay.
5 Apatite. Apatite is a mineral in vertebrate bones and teeth.
6 Orthoclase, Orthoclase is a feldspar, and in German, "feld" means "field".
7 Quartz. Quartz is the most common mineral in the Earth's crust.
8 Topaz. Includes emerald and aquamarine which are varieties of beryl
9 Corundum. Sapphire and ruby are varieties of corundum. Twice as hard as topaz.
10 Diamond. Used in jewelry and cutting tools. Four times as hard as corundum.
As a comparison, here are some hardnesses of some other items:
2.5 Fingernail.
2.5-3 Gold, Silver
3 Copper penny
4-4.5 Platinum
4-5 Iron
5.5 Knife blade. So the field test to check whether something is Gypsum or Quartz is to drag a penknife blade over it. If the knife marks it, it's gypsum, if the mineral marks the blade, it's quartz.
6-7 Glass
6.5 Iron pyrite
7+ Hardened steel file
>10 Wurtzite Boron Nitride
>10 Lonsdaleite (Hexagonal Diamond)
I'm still waiting for someone do Moe's scale of hardness as to how tough the patrons of his bar are in the Simpsons...
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Orangutangents
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