When did people start mining? Detailed answer

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When did people start mining? Detailed answer

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When did people start mining?

Minerals are chemical substances or compounds that occur in the bowels of the earth in their natural form. Ore is a deposit rich in some mineral for which it is mined. No one knows exactly when mining began. One of the first mining enterprises recorded in history was the Egyptian expedition to the Sinai Peninsula around 2600 BC. e. They went to mine mica, and discovered and extracted a more useful mineral - copper.

The ancient Greeks mined silver in mines south of Athens in 1400 BC. e. The Greeks built mines around 600-350 BC. e. Some of the wells were up to 120 m deep. Later, other metals such as lead, zinc, and iron were mined from these same spears. In order to supply the huge empire, the Romans carried out mining on a large scale. Their mines were everywhere - from Africa to Britain.

Among the most valuable Roman mines was that of Rio Tinto in Spain, which produced large quantities of gold, silver, copper, tin, lead and iron. Mining reached a large scale in the XNUMXth century, when the industrial revolution began. A large amount of coal was required for metallurgy and factory furnaces.

Therefore, coal mining developed rapidly. Modern mining technology was born at that time. In the 1848th century, the so-called "gold rush" broke out in the United States. It began in California in 500. Over the years, more than $XNUMX million worth of gold has been mined there.

In 1896, the "gold rush" swept Alaska. In South Africa, the largest deposits of diamonds were discovered in 1870, and rich gold deposits were discovered in 1886.

Author: Likum A.

Random interesting fact from the Great Encyclopedia:

Who is called a mentally retarded child?

A person whose mental development stops before it reaches the normal level for people is called mentally retarded. Mental retardation, or dementia, cannot be regarded as a specific disease. Rather, it is just a sign, or, as doctors say, a symptom of an illness or that not everything is in order in the body.

Dementia can have different causes, and not all of them are well understood. But this phenomenon should make itself felt before the age of seventeen, when the mental development of a person basically ends. Although there is no consensus among experts on this issue, most believe that a person’s mental abilities can be measured using special tests. The results of this test of mental development are expressed in the so-called indicator of mental development, or the coefficient of giftedness, which in a normally developed average person is considered equal to 100.

A person whose IQ is below 70 and who is unable to cope independently with the problems of daily life is considered demented. There are four degrees of mental retardation: minor, moderate, major and profound. The index of mental development in the severely and profoundly retarded falls below the mark of 35. Their mental abilities are not higher than those of normal five-year-old children. They cannot serve themselves and are unable to protect themselves from danger. Someone has to keep an eye on them all the time.

With moderate and slight retardation, there are fewer problems. They can learn to perform simple tasks by working in special workshops. They have difficulties with reading, writing and arithmetic, but they are able to master most of the primary school subjects. Mental retardation can be caused by various reasons, among which are diseases of the mind and body, and even the difficult conditions in which the child lives. Scientists have established about two hundred factors that contribute to the development of dementia. These include birth trauma, brain tumors, blood disorders, infectious diseases caused by certain viruses, and various types of congenital dementia.

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Smart tungsten coating will replace paper 09.11.2016

Scientists have created a reusable paper-like coating that is designed to reduce the consumption of paper products to restore the planet's ecology. You can "draw" on such a coating using UV radiation.

Digital media is ubiquitous in today's society, but sometimes an electronic screen is simply not enough, or it costs an unreasonable amount of money to use. The typical office worker still prints thousands of pages of paper documents a year, and large posters and banners remain the norm at trade shows and conferences. To reduce the environmental impact and reduce paper consumption, engineers have created a paper-like coating that can be cleaned and reused up to 40 times after use without losing image quality.

The flexible membrane is made of tungsten oxide. Similar technologies are used in "smart" windows, which control the amount of light and heat passing through them using water-soluble polymers. "Printing" on the membrane surface occurs by selective exposure to ultraviolet light, as a result of which the colorless tungsten oxide begins to turn blue. Changing the light takes only a few seconds, which is much faster than in previous similar experiments. The pattern will naturally fade in the presence of oxygen, but will still remain visible for several days under normal atmospheric conditions.

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The researchers suggest that a commercial version of this technology can be released to the market relatively easily. The raw materials for making membranes are commercially available, and UV lamps are often used to sterilize food and equipment, so they are also easy to get. As specific applications, the scientists suggest embedding membranes in fabric to create a kind of "customizable" garment that can be painted as desired. The same applies to posters and billboards, which can be redrawn every time on the old surface.

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