 |
20. Answer the questions. 21. Match the gemstone with the correct description. 22. Give the definition for the next terms.
|
|
|
|
20. Answer the questions.
1. What are the most valuable gemstones?
2. What is diamond composed of?
3. What properties make diamond the world's most desirable gemstone?
4. What are similarities and differences between ruby and sapphire?
5. What type of beryl is called emerald?
6. What is aquamarine?
21. Match the gemstone with the correct description.
| 1. Diamond 2. Sapphire 3. Ruby 4. Emerald 5. Aquamarine | a) is a gemstone and a variety of the mineral beryl colored green by trace amounts of chromium. It has a hardness of 7. 5–8 on the Mohs scale. b) is considered one of the four precious stones, together with sapphire, emerald and diamond. It has a hardness of 9. 0 on the Mohs scale of mineral hardness. It is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminum oxide). c) it is a gemstone variety of the mineral corundum. It has the remarkable hardness - 9 on the Mohs scale (the third hardest mineral). The luster is vitreous. The streak is white. Although blue is the most well-known color of this mineral, it may also be colorless, purple, yellow and green. d) is a gemstone which name comes from Latin means " water of the sea" It is brittle, has imperfect cleavage and hexagonal crystal structure. It is a blue variety of beryl. e) is one of the four most valuable stones which name is derived from the ancient Greek α δ ά μ α ς, " unbreakable". It has perfect cleavage in four directions. The luster is adamantine. The streak is colorless. It is a colorless transparent gemstone made of pure carbon, and it is the hardest substance known. |
22. Give the definition for the next terms.
Model: Olivine is ______ that ______
Olivine is a very common silicate mineral that forms at depth, crystallizing from magma under high temperatures and pressures.
1) Minerals are ______ that ______
2) Quartz is ______ that ______
3) Feldspar is ______ that ______
4) Diamond is ______ that ______
5) Ruby is ______ that ______
6) Sapphire is ______ that ______
7) Emerald is ______ that ______
24. From the library or on the internet, find out about a mineral and be ready to speak about it.
UNIT III
IGNEOUS, SEDIMENTARY AND METAMORPHIC ROCKS
Start-up.
What is a rock?
What is the difference between rocks and minerals?
How many types of rocks do you know? What are they?
1. Read and learn the following words.
| 1. basalt [`bæ sɔ ː lt] – базальт 2. clay [kleɪ ] – глина 3. gabbro [ʹ gæ brə ʋ ] – габбро 4. gneiss [naı s] – гнейс 5. granite [ʹ græ nı t] – гранит 6. gravel [ʹ græ vl] – гравий 7. limestone [ˈ laɪ mstə un] – известняк 8. magma [ʹ mæ gmə ] – магма 9. marble ['mɑ ː bl] – мрамор 10. sandstone [ʹ sæ ndstə ʋ n] – песчаник 11. shale [ʃ eı l] – сланец 12. composition – состав 13. origin – происхождение 14. texture – структура 15. solid - твердый 16. majority – большинство 17. major – главный, основной 18. layer (stratum, мн. ч. strata) – пласт 19. size - размер 20. shape - форма 21. to originate - образовываться; появляться 22. to deposit - откладываться 23. to accumulate - накапливаться 24. substance - вещество 25. particle - частица 26. grain – зерно 27. coarse-grained – крупнозернистый 28. fine-grained – мелкозернистый | 29. pure – чистый, без примесей 30. sedimentary rock – осадочная порода 31. igneous rock – магматическая порода 32. metamorphic rock – метаморфическая порода 33. intrusive igneous rock – интрузивная магматическая порода 34. extrusive igneous rock –экструзивная магматическая порода 35. fragmental (clastic) sedimentary rock – обломочная (кластическая) осадочная порода 36. chemically precipitated sedimentary rock – хемогенная осадочная порода 37. organic (biogenic) sedimentary rock – органогенная осадочная порода 38. amount – количество 39. porosity – пористость 40. permeability – проницаемость 41. stratification – слоистость, расслоение, напластование 42. to precipitate – выпадать в осадок 43. to dissolve – растворять 44. solution – раствор |
2. Read the text and translate it into Russian.
|
|
|
Igneous, Sedimentary and Metamorphic Rocks
| A rock is a solid cumulative of minerals located in the earth's lithosphere. They are generally classified into igneous, sedimentary, and metamorphic rocks, on the basis of their mineral, chemical, and textural composition. While studying the characteristics of these rocks, it is essential to be aware about the processes that are responsible for their formation. Metamorphic rocks. Metamorphic rocks are formed when other types of rocks change because of the enormous pressure and heat they experience deep within the earth. Metamorphism is a geological process involving rocks changing their form. The process requires millions of years in transformation. Earlier, the transformed rocks could either have been igneous, sedimentary, or even older metamorphic rocks. The heat and pressure of the Earth's crust bring about profound changes in terms of physical as well as chemical properties, and give new textures to the rock. The new texture that develops is through the process of recrystallization. Some examples of metamorphic rocks are gneiss, marble, and quartzite. | |||||
| Igneous rocks. Igneous rocks are formed when magma (molten rock) cools and solidifies, either on the surface of the Earth, or beneath the Earth's crust. Depending on where their formation takes place, igneous rocks are categorized into two groups –extrusive igneous rocks and intrusive igneous rocks. When magma comes to the surface of the Earth as a result of some volcanic activity and solidifies to become a rock, |
| ||||
| this rock is referred to as an extrusive igneous rock. On the other hand, when magma seeps in between the layers of sedimentary rocks beneath the crust and solidifies to form a rock, it is referred to as an intrusive igneous rock. Sedimentary rocks. Sedimentary rocks are formed by the deposition of material at the Earth’s surface and within bodies of water. Sedimentation is the collective name for processes that cause minerals or organic particles to settle and accumulate or minerals to precipitate from a solution. Particles that form a sedimentary rock are called sediments. Sedimentary rocks are classified into three groups: fragmental (or clastic), chemically precipitated and organic (biochemical or biogenic). | |||||
| Clastic sedimentary rocks are composed of fragments or clasts of materials derived from other rocks. They are composed largely of quartz, feldspar, and clay minerals. Biochemical sedimentary rocks made from the fossil remains of animals and plants. They contain materials generated by living organisms. They often include fragments of bones and shells. Chemically precipitated sedimentary rocks consist of material that was precipitated out of solution, such as by the evaporation of water they were dissolved in. In general, a sedimentary rock is formed in four basic stages: 1) weathering of pre-existing rock; 2) transportation of the sediment by agents such as water, ice, or wind; 3) deposition of the sediment; and 4) conversion into new rock by processes such as compaction, cementation, and recrystallization. | 
| ||||
(from: http: //www. buzzle. com/articles/igneous-sedimentary-and-metamorphic-rocks. html)
|
|
|
