Geoscience Reference
In-Depth Information
5.2.2
The Finest Minerals
Clay particles have strange properties and characteristics when compared to silt and
sand particles. First of all, they do not have a spherical shape or the shape approxi-
mately modeled by a sphere. Second, they are not grains. And third, although they
could be closely compared to fl akes or to very thin disks, each of them has a specifi c
crystal lattice. Indeed, they are
clay minerals
. We authors do understand that it looks
like a sort of typing error when two words standing in opposition in our instinctive
imagination are put together:
clay
and
minerals.
When we stir wet clay in our fi n-
gers, we get the feeling like stirring butter. But minerals have sharp edges, we know
it by our observation of many silicate crystals in museum or when we visited the
collection of crystals of our friends or when we watched the expensive gems in the
store windows of the jewelers. What happened with the sharpness of minerals if the
size is decreased to such a minimum as less than 0.002 mm or in other units less
than 2
m? Wet clay is well formed keeping the form even if dried in an oven, and
this baking fi xes the form, while sand consisting of visible minerals cannot keep the
form when it loses only a part of its original water. All those contradictions will be
explained rationally when we apply the recent advanced methods of study of
minerals.
When I (MK) studied about 55 years ago to learn how clay minerals infl uence
water and as a consequence the water regime in soils, my friends studying literature
theory, history, or philosophy at the Charles University used to ask me about my
postgraduate studies at the Technical University and what kind of balmy research
did I explore. When I responded that I made experiments with clay minerals to
understand their infl uence on the physical properties of water in soil, they were
thinking aloud that I bound one clay mineral to a cotton thread, immersed it in
water, and observed what was happening. I tried to explain to them that nothing like
that was feasible. I attempted to persuade them that even the thinnest thread was
extremely thick for a particle of clay and that their imagination was on the level of
thinking that I tried to fasten an ant to a hawser or anchor rope. Some nodded their
heads in agreement and asked if I used technical equipment like a magnifying glass,
while others, not asking at all, whispered that I was “around the bend” or “tetched”
in the head.
The knowledge that all clays are not the same was known in China 3,600 years
ago. They knew how to select specifi c places between various localities having
whitish clay that had properties of plastic paste after being wetted. The Chinese
formed the paste into a cup or some kind of small sculpture that kept its original
shape after being dried and baked. Improving these procedures, they produced the
fi rst porcelain about 2,200 years ago. The technology continued for 1,600 years
until the Chinese porcelain was imported to Venice, to the Medici family, and to the
courts of kings in Europe. People were shocked by the intricate porcelain shapes
and by the near transparency of the walls of cups. Astonishment and wonderment of
the Chinese products was so strong in England that the nobility referred to the newly
imported goods as
china
and the term started to be broadly used in English. The raw
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