- •Assignments
- •1. Answer the questions.
- •2. Divide the complex sentences into simple ones.
- •4. Replace the Russian words in the brackets with their English equivalents.
- •5. Find the synonyms to the following words in the text.
- •7. Say if the following statements correspond to the text. Correct the wrong ones.
- •8. Speak on the following topics.
- •Assignments
- •1. Answer the questions.
- •2. Translate the following words and word-combinations.
- •3. Replace the Russian words in the brackets with their English equivalents.
- •4. Find the synonyms to the following words in the text.
- •5. Read the dictionary definitions and find the defined words in the text.
- •7. Point out the main ideas of the text. Make a list of them. Unit II rock-forming minerals
- •Assignments
- •1. Answer the questions?
- •3. Replace Russian words in the brackets by their English equivalents.
- •4. Find the synonyms to the following words in the text.
- •5. Match the terms on the left with their definitions on the right. Use them in sentences of your own:
- •6. Say if the following statements correspond to the text. Correct the wrong ones.
- •7. Make a list of basic properties of rock-forming minerals and speak on each of them.
- •What makes a gemstone?
- •Assignments
- •1. Answer the questions.
- •2. Suggest the Russian for:
- •3. Replace the Russian words in the brackets with their English equivalents.
- •4. Find the synonyms to the following words in the text.
- •5. Read the dictionary definitions and find the defined words in the text.
- •6. Mark the following sentences as True (t) or False (f). Correct the wrong ones.
- •7. Speak on the following topics.
- •The nature of rocks
- •Assignments
- •6. Fill in the gaps with the words and expressions from the text.
- •8. Point out the main ideas of the text. Make a list of them. Sedimentary rocks
- •Assignments
- •1. Answer the following questions:
- •7. Analyze the diagram and speak on it.
- •Igneous rocks
- •Assignments
- •1. Answer the following questions:
- •2. Find in the text the English equivalents for the Russian words and expressions. Reproduce the contexts in which they are used.
- •4. Fill in the gaps with the words and expressions from the text.
- •6. Speak on the following topics:
- •7. Find 9 geological terms.
- •Metamorphic rocks
- •Assignments
- •1. Find in the text the English equivalents for the Russian words and expressions. Reproduce the contexts in which they are used.
- •2. Suggest the Russian equivalents.
- •4. Fill in the gaps with the words and expressions from the text.
- •5. Mark the following sentences as True (t) or False (f). Correct the wrong ones.
- •7. Translate the following questions and answer them:
- •8. Speak on the following topics:
7. Point out the main ideas of the text. Make a list of them. Unit II rock-forming minerals
Since most rocks contain minerals, some knowledge of minerals is necessary to identify rocks. Because minerals are chemicals, they have special properties which aid in their recognition. Minerals are easily identified by chemical analysis.
One of the properties of minerals which depends on their chemical composition is the specific gravity or relative weight of the minerals. When molecules are packed together with a minimum of waste space, as in the metals, the mineral weighs more. The specific gravity of minerals is compared to water, which has a specific gravity of 1. Common minerals range from 1.7 specific gravity, for borax, to 19.3, for gold.
Most minerals also have a distinct crystal form. This, in turn, depends on the arrangement of the molecules in each mineral. Mineral crystals fall into six systems, and these can be identified by the angles of the crystal. Even a small fragment of a crystal is enough to give a clue to its structure and its crystal form.
The way a mineral breaks in flat planes is called its cleavage. This, too, can be used in identification. Mica is an example of perfect cleavage. Minerals also break in an irregular way. This kind of breakage is called fracture and it, too, helps to identify a mineral.
All minerals have a definite hardness, which is the mineral's ability to scratch or be scratched. Hardness is generally measured on an arbitrary scale of 10.
The color of minerals is not important in identification because the color may be due to impurities or surface changes. Streak is the color of a powdered mineral, and luster is the way the structure of a mineral reflects or breaks up light. Besides these properties, certain minerals respond to ultra-violet light and give off brilliant colors. This fluorescence is also used in identification. Other minerals are magnetic. Some have electrical radioactive properties. These and many other properties of minerals help identify them in the field and in the laboratory.
The rock-forming minerals are a group of little importance as gems or as sources of metal. But they have great importance in the overall history of the earth. The rock-forming minerals are the ones which make our land on which we live.
Assignments
1. Answer the questions?
Why is knowledge of minerals necessary?
What are the basic properties of minerals?
What is specific gravity?
What does the crystal form depend on?
What are cleavage and fraction? How do they differ?
What is hardness? How is it measured?
Is colour important in identification of minerals?
What are other properties of minerals?
Why are minerals important?
2. Find Russian equivalents to English words and expressions.
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