Реферат по предмету "Иностранный язык"


Emeralds Essay Research Paper Emeralds The Emerald

Emeralds Essay, Research Paper

Emeralds

The Emerald is a rich green stone that can be more valuable than a diamond of the same size. Emeralds are part of the beryl family of precious stones. They have a hardness of 8 and a sp.gr of 2.7 to 2.9. The emerald is considered a gem, or a mineral that is desired for its beauty and durability. A large number of minerals are considered gems. Emeralds and beautiful stones like it have their value determined by four different factors: the beauty of the stone, how rare the stone is, the stone s hardness and toughness, and the way the stone has been cut or polished. The emerald itself is used mostly for jewelry and must be cut into a certain shape.

The history of the emerald goes back to ancient times when the gem was considered to have healing powers of the eye. Emeralds in ancient times were mostly mined in Egypt, where they were greatly valued and only members of the upper class owned them. Today the emerald is mined in several different countries, but the main supplier is the South American country of Columbia. The Inca mined the Columbian emerald in ancient times before the Spanish arrived. The world s largest emerald however was mined in the Ural Mountains of Russia. The emerald weighed six pounds and is now on display in the Leningrad museum.

The emerald is a type of beryl, or a valuable gem material that is also a mineral. Beryl is chemically consisted of aluminum beryllium silicate. The chemical formula for beryl (and the emerald) is Be3Al2(SlO 3)6. The pure type of beryl is colorless and clear. Other stones that are also forms of beryl include: aquamarine, morganite, golden beryl, and rose beryl. Beryl usually forms in a hexagonal shape, which gives the stone eight different sides. Beryl can come in several different colors, but emeralds usually only come in green. The emerald gets its greenish color from the small amounts chronic oxide inside it. Emeralds do not have as such large crystals as pure beryl, and can be split into thin slices like a loaf of bread, also making it different from beryl.

The emerald is a very unique stone because it is the softest and only second in money value behind a flawless ruby. Geologists use an instrument called a refractometer to determine how well the stone refracts light and its type, which cannot always be told by just looking at it. The value of beryl depends on it s hardness, transparency, and color. Emeralds fetch such high prices because the supply is very limited, and flawless emeralds are very rare. Columbia s government really limits the amount of emeralds that make the market, so that also drives up prices.

Many gem industries have discovered a way to make a synthetic emerald, and it is often hard to tell the real ones from the fake ones. One method though, is putting the gem in a light and seeing how well it will reflect the light. Chemical tests can also tell which emeralds are synthetic.

Emeralds and other types of beryl can be used in industry too. Beryl is a major ore of beryllium that is used to make a metal called beryllium-copper. Beryllium-copper is used to make metals in jets, reactors, and some other important equipment. Superstition states that staring at an emerald will improve your eyesight and take away the need for glasses.

Overall, the emerald is a very amazing gem. No other object is said to have a better shade of green than an emerald. It is a very useful stone that has been admired for thousands of years and probably will be admired for thousands more.




Не сдавайте скачаную работу преподавателю!
Данный реферат Вы можете использовать для подготовки курсовых проектов.

Поделись с друзьями, за репост + 100 мильонов к студенческой карме :

Пишем реферат самостоятельно:
! Как писать рефераты
Практические рекомендации по написанию студенческих рефератов.
! План реферата Краткий список разделов, отражающий структура и порядок работы над будующим рефератом.
! Введение реферата Вводная часть работы, в которой отражается цель и обозначается список задач.
! Заключение реферата В заключении подводятся итоги, описывается была ли достигнута поставленная цель, каковы результаты.
! Оформление рефератов Методические рекомендации по грамотному оформлению работы по ГОСТ.

Читайте также:
Виды рефератов Какими бывают рефераты по своему назначению и структуре.