Jackie Thompson, age ll, of Oakland, Calif., for her question:
How is coal turned into diamonds?
The basic material in coal is carbon and diamonds are made entirely of carbon atoms. Both coal and diamonds are made in the earth's crust, but very different recipes are used to make them. Coal is not a step in the diamond making process and our coal deposits are not destined to become vast layers of glittering diamonds.
Only l3 elements in the earth's crust are more plentiful than carbon. Its atoms are used by all plants and animals to make hydrocarbon molecules and they are present in all organic chemicals. Its atomic number is six, which means that its atom has six protons in the nucleus and an orbiting system of six electrons. Carbon is one of life's vital elements and united with other elements it forms thousands of chemical compounds.
Charcoal, made mostly from carbon, was known in prehistoric times. sooty smoke is made mostly of carbon particles and so is the lead in a pencil. This so called lead is a soft, waxy mineral called graphite and most graphite is the final stage in the earth's coal making recipe. And a sparkling diamond also is a form of pure carbon.
The making of coal is a slow process taking millions of years. It begins when masses of vegetation become buried in the ground. The bacteria that normally cause plants to decay are not present and the material fails to rot. Instead it becomes crushed under heat and pressure. Liquids and light gases are squeezed out of the material and the carbons are left behind. Gradually the coal deposit becomes more and more carbonized until it becomes oily, black graphite.
The carbon atoms in graphite are loosely packed together in careless arrangements. The carbon atoms in a diamond are arranged in a tightly packed crystal pattern. The crystal is very dense and diamond weighs three and one half times more than an equal volume of water; graphite only two and one half times.
In nature such crystals may form from atoms deposited by water or under terrific heat and pressure. Diamonds are formed in the fury of volcanic activity and We find them in the vents and tubes of ancient volcanoes. They form from carbon atoms present in the seething lava and the recipe may be finished in a short period of fierce heat and pressure.
The shape of a crystal depends upon the shape of its individual particles. The diamond follows an eight sided octahedron pattern shaped like two pyramids sharing the same base. Diamonds in the rough may be octahedrons, cubes or round masses coated with dark crust. But when broken apart the planes and angles tend to split into octahedron patterns. And nature transforms only small traces of her carbon atoms into hard, dense crystals of diamonds.