The ancient
inventor of glass, perhaps only vaguely guessed that the white sand that he
used to make glass and quartz crystals were “relatives”. And now, when
millennia have passed, we marvel at the fidelity of his observations. After
all, we already know that sand and quartz consist of the same chemical
elements: silicon and oxygen.
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| Onyx |
Scientists have
called this compound silica. Nature gave silica a wide variety of forms:
transparent quartz crystals sparkling in the sun, like clear water of a stream,
for which they are also called rock crystal. Black agate, onyx, and precious
jasper. Violet amethyst and whetstone, river pebbles rolled in water and opal -
all this is silica.
Silica is also
found in wildlife. It is a material of shells of algae called diatoms and
openwork skeletons of microscopic living creatures — radiolarians. It permeates
thin straws of cereals and makes bamboo tubes strong. It participates wherever
a strong structure is required in nature.
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| Jasper |
Silica in the form
of sand or crushed quartz crystals can be melted with obtaining the liquid from
it. And the cooled liquid turns into colorless transparent glass. But in order
to melt silica, you need a temperature of two thousand degrees.
Ancient
glassmakers could not get such a high temperature. The experience helped them -
they found that adding soda or potash to the sand significantly reduces its
melting point. They also noticed such details: soda gives glass softness, and
potash gives hardness. Then the masters realized: they also need lime,
otherwise the glass will dissolve in water. Furthermore: the addition of lead
oxide gives the glass a shine; magnetite ore - a deep black color; tin oxide -
milky white; chrome ores stain glass green, and copper gives cherry color.
