以how is glass made 为题弄一篇小短文,朗读2分钟左右

以how is glass made 为题弄一篇小短文,朗读2分钟左右
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短点的啊~~这么长

In nature, glass can be formed in three ways:
1.When lightning strikes sand – The energy from lightning that strikes a sandy beach or sandy soil fuses natural silica glass (called lechatelierite) into fragile forms called fulgurites. These branch-like formations in the ground can range from two centimeters to three inches in diameter, and up to several feet long. The tan or grayish exterior of a fulgurite is crusty and sandy, but the interior is lined with bubbly glass. Sand fulgurites are commonly found in Florida—a state with a high number of lightning strikes—the shores of Lake Michigan, and the Atlantic coast. Fulgurites are very fragile so must be carefully excavated.
2.When lightning strikes rocks – Rock fulgurites are formed when lighting strikes a rocky surface, and this commonly occurs on mountain peaks. Rather than the branch-like form of a sand fulgurite, a rock fulgurite appears as a thin, glassy crust on the rock’s surface. It has glass-lined bubbles or cavities. The glass has less silica than in sand fulgurites, and the colors are influenced by the mineral composition of the rock that was struck.
3.When a meteorite collides with Earth – Another natural phenomenon that creates glass is when a meteorite strikes Earth. Parts of the outer crust are heated and suddenly cooled at impact, forming small objects, called tektites, which are scattered into enormous debris fields. They contain approximately 70 percent silica. Scientists first thought tektites, which are from 800,000 to over 64 million years old, originated from space, but now understand that they were most likely sedimentary rocks on Earth. It is interesting that tektites are found on all continents except Antarctica and South America, and their size, shape and composition vary depending on the regions in which they are found. Some tektites are located in or near large craters, others mixed in with ordinary gravel and coarse sediment.
Atomic Bomb Formed Glass
One way that glass was formed naturally but with man’s influence was through the first atomic explosion. When the nuclear bomb was detonated in New Mexico in 1945, the crater that it formed became coated with a grayish-green colored silica glass that was called “trinitite” because the test was conducted at Trinity Site. The extreme heat of the explosion had melted sand in the remote, desert location and converted it to glass.
The Basic Ingredients Man Uses to Make Glass
To make glass, people use a basic recipe of sand (silicon dioxide), soda ash (sodium carbonate) and limestone (calcium carbonate). The peoples of ancient Mesopotamia probably inadvertently made glass for the first time when they fired pottery, as the sand and minerals were fused to a glaze on their pieces. In ancient days, the mineral natron (hydrated sodium carbonate)—which was used in embalming and ceramics—was used for the soda ash.
Before man learned the secret of glassmaking, nature was the world's only glassmaker. Lightning striking sand melted it into long, thin tubes of glass, and volcanoes erupting melted rocks and sand into glass.
Man's earliest glass was probably a glaze on ceramic pottery made somewhere around 3000 B.C.
Today, three inexpensive ingredients, sand, soda ash, and lime, are melted together to make glass. This is done in large furnaces at high temperatures until the mixture become a syrupy mass. When this syrup cools, it is glass.
When glass is in a melted state, it can be shaped by many methods, but the most common are blowing, pressing, and drawing.
Blowing is the oldest method of working with glass, dating back thousands of years. A ball of molten, or melted, glass is put on the end of a hollow iron pipe, and a worker blows gentle into the pipe (much like the way you blow soap bubbles) until the glass takes the shape and thinness the blower wants. During this process, the glass is constantly reheated to keep it soft and workable.
When the glass is shaped to the blower's satisfaction into a bottle or a vase, it is broken from the pipe. Although glass blowing by hand is still done today, it can also be done by machine.
In the pressing method, a hot glob of glass is dropped into a mold, then pressed with a tool, so the glass fills the inside of the mold. Ashrays, baking dishes, and glass containers are made this way.
The drawing method shapes glass flat, as for windows and mirrors, or into tubes, as for fluorescent lights, TV tubes, and laboratory equipment. To make flat glass, first the melted glass is drawn into a tank of melted tin. The tin's perfectly smooth surface forms a smooth layer of glass as the glass floats on top of the tin. To make glass tubing, a stream of molten glass is drawn around the inside of a cylinder. As the cylinder rotates, air is blown through it, forming a continuous tube out of the glass.
No matter which method is used, the glass must still go through a process called annealing. In annealing, the glass is reheated and gradually cooled to restore its strength and prevent its shattering. Tempering is also used to strengthen glass. In tempering, the glass is reheated, then chilled by sudden blasts of cold air.
This process should not be confused with another method called lamp working, in which finished glass tubes are heated over a blowtorch, and as the glass worker bends, twists, and stretches the glass, he can create miniature animals, ships, and baskets.
Banks, tanks, aircraft, and some government cars have glass so thick and with so many layers that it can stop a bullet even at close range!