Stones are interesting.
This page is a memo of my knowledge.
Pure metal is also explained as stones here.
Geology studies the climate and eco-system in the ancient ages.
It tells us the history of the earth.
And it is a basis of environmental studies.
Stone tell us the condition of the land in a long period.
So stone is an environmental index.
We use crystallography to study stones.
But stones in the nature are not pure crystals.
Those are containing impurities or combination of crystals or non-crystal.
Main substance of many stones is silicon (Si).
Crystal of silicon has same structure to diamond.
Silicon is material of silicon wafer.
Silicon wafer is a basis of semiconductors.
Semiconductors are main parts of computers.
So silicon supports Data Science.
Silicon is also a material of a solar battery.
Silicon is needed both solar batteries and silicon wafers.
Crystal of silicon dioxide (SiO2) is quartz.
Beautiful quartz is called "crystal".
Silicon dioxide is a material of a glass.
To get gold, destruction of the environment and health problem occur.
Diamond has similar problems.
It is a cause of crimes.
Rare metal has the problem of shortage.
Some stones are said ,"enhance concentration", "make dreams come true".
Those are called, "power stones".
The prices of stones are depended on the property and rareness.
If main substances are same, a small amount of impurities changes the color, name and price of the stone.
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