2015-03-22
422
1. Learn the words and word combinations before reading:
occur - [q'kW] - залегать, встречаться, происходить
occurrence - [q'kArqns]– месторождение минерала, место залегания руды
crystalline structure -['kristqlain] - кристаллическая структура
common - ['kPmqn]– широко распространенный
halide - [ʹhælaıd] - галоидное соединение, галид
sulfide -['sAlfaId] - сульфид, сернистое соединение
sulfate - ['sAlfeIt] - сульфит, соль серной кислоты
luster - ['lAstq]– глянец, блеск
constituent - [kqn'stItjuqnt] – составная часть, элемент
transparent - [trxn'spxrqnt] - прозрачный
brittle - ['brItl]– хрупкий, ломкий. неустойчивый
effervesce - ["efq'ves] - выделяться в виде пузырьков, шипеть
substitute for – заменять на что-либо, подменять
2. Read and translate the text:
Most rocks are composed of minerals. Minerals are defined by geologists as naturally occurring inorganic solids that have a crystalline structure and a distinct chemical composition. Of course, the minerals found in the Earth's rocks are produced by a variety of different arrangements of chemical elements. A list of the eight most common elements making up the minerals found in the Earth's rocks is described in Table 1.
| Element | Chemical Symbol | Percent Weight in Earth's Crust |
| Oxygen | O | 46.60 |
| Silicon [ʹsılıkən] | Si | 27.72 |
| Aluminum [əʹlu:mınəm] | Al | 8.13 |
| Iron [ʹaıən] | Fe | 5.00 |
| Calcium | Ca | 3.63 |
| Sodium | Na | 2.83 |
Over 2000 minerals have been identified by earth scientists. Table 2 describes some of the important minerals, their chemical composition, and classifies them in one of nine groups.
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The Element Group includes over one hundred known minerals. Many of the minerals in this class are composed of only one element. Geologists sometimes subdivide this group into metal and nonmetal categories. Gold, silver, and copper are examples of metals. The elements sulfur and carbon produce the minerals sulfur, diamonds, and graphite which are nonmetallic.
| Table 2: Classification of some of the important minerals found in rocks. | ||
| Group | Typical Minerals | Chemistry |
| Elements | Gold | Au |
| Silver | Ag | |
| Copper | Cu | |
| Carbon (Diamond and Graphite) | C | |
| Sulfur | S | |
| Sulfides | Cinnabar [ʹsınəbɑ:] | HgS |
| Galena [gəʹli:nə] | PBS | |
| Pyrite [ʹpaı(ə)raıt] | FeS2 | |
| Halides | Fluorite [ʹflʋ(ə)raıt] | CaF2 |
| Halite [ʹhælaıt] | NaCl | |
| Oxides | Corundum [kəʹrʌndəm] | Al2O3 |
| Cuprite [ʹkju:praıt] | Cu2O | |
| Hematite [ʹhi:mətaıt] | Fe2O3 | |
| Carbonates (Nitrates and Borates) | Calcite [ʹkælsaıt] | CaCO3 |
| Dolomite [ʹdɒləmaıt] | CaMg(CO3)2 | |
| Malachite [ʹmæləkaıt] | Cu2(CO3)(OH)2 | |
| Sulfates | Anhydrite [ænʹhaıdraıt] | CaSO4 |
| Gypsum [ʹdʒıps(ə)m] | CaSO4 -2(H2O) | |
| Phosphates (Arsenates, Vanadates, Tungstates, and Molybdates) | Apatite [ʹæpətaıt] | Ca5(F,Cl,OH)(PO4) |
| Silicates | Albite [ʹælbaıt] | NaAlSi3O8 |
| Augite [ʹɔ:dʒaıt] | (Ca, Na)(Mg, Fe, Al)(Al, Si)2O6 | |
| Beryl [ʹberıl] | Be3Al2(SiO3)6 | |
| Biotite [ʹbaıətaıt] | K (FE, Mg)3AlSi3O10(F, OH)2 | |
| Hornblende [ʹhɔ:nblend] | Ca2(Mg, Fe, Al)5(Al, Si)8O22(OH)2 | |
| Microcline | KAlSi3O8 | |
| Muscovite [ʹmʌskəvaıt] | KAl2(AlSi3O10)(F, OH)2 | |
| Olivine [ʹɒlıvi:n] | (Mg, Fe)2SiO4 | |
| Orthoclase [ʹɔ:θəkleıs] | KAlSi3O8 | |
| Quartz [kwɔ:ts] | SiO2 | |
| Organics | Amber [ʹæmbə] | C10H16O |
The sulfides form an economically important class of minerals. Many of these minerals consist of metallic elements in chemical combination with the element sulfur. Most ores of important metals such as mercury (cinnabar - HgS), iron (pyrite - FeS2), and lead (galena - PbS) are extracted from sulfides. Many of the sulfide minerals are recognized by their metallic luster. But on account of their usual sparing occurrence in rocks only one of them, pyrite, has a special importance as a rock – making mineral.
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The halides are a group of minerals whose principle chemical constituents are fluorine, chlorine, iodine, and bromine. Many of them are very soluble in water. Halides also tend to have a highly ordered molecular structure and a high degree of symmetry. The most well-known mineral of this group is halite (NaCl) or rock salt.
The oxides are a group of minerals that are compounds of one or more metallic elements combined with oxygen, water, or hydroxyl (OH). The minerals in this mineral group show the greatest variations of physical properties. Some are hard, others soft. Some have a metallic luster, some are clear and transparent. Some representative oxide minerals include corundum, cuprite, and hematite.
The carbonates consist of minerals which contain one or more metallic elements chemically associated with the compound CO3. Most carbonates are lightly colored and transparent when relatively pure. All carbonates are soft and brittle. Carbonates also effervesce when exposed to warm hydrochloric acid. Most geologists considered the Nitrates and Borates being subcategories of the carbonates. Some common carbonate minerals include calcite, dolomite, and malachite.
The sulfates are a mineral group that contains one or more metallic element in combination with the sulfate compound SO4. All sulfates are transparent or translucent and soft. Most are heavy and some are soluble in water. Rarer sulfates exist containing substitutes for the sulfate compound. For example, in the chromates SO4 is replaced by the compound CrO4. Two common sulfates are anhydrite and gypsum.
The phosphates are a group of minerals of one or more metallic elements chemically associated with the phosphate compound PO4. The phosphates are often classified together with the arsenate, vanadate, tungstate, and molybdate minerals. One common phosphate mineral is apatite. Most phosphates are heavy but soft. They are usually brittle and occur in small crystals or compact aggregates.
The silicates are by far the largest group of minerals. Chemically, these minerals contain varying amounts of silicon and oxygen. It is easy to distinguish silicate minerals from other groups, but difficult to identify individual minerals within this group. None are completely opaque. Most are light in weight. The construction component of all silicates is the tetrahedron. A tetrahedon is a chemical structure where a silicon atom is joined by four oxygen atoms (SiO4). Some representative minerals include albite, augite, beryl, biotite, hornblende, microcline, muscovite, olivine, othoclase, and quartz.
The organic minerals are a rare group of minerals chemically containing hydrocarbons. Most geologists do not classify these substances as true minerals. Note that our original definition of a mineral excludes organic substances. However, some organic substances that are found naturally on the Earth that exist as crystals resemble and act like true minerals. These substances are called organic minerals. Amber is a good example of an organic mineral.
Notes:
* on account of - из-за, вследствие, на основании
3. Read the following sentences and say if they are taken from the text or not, if they are not correct, correct them.
1. According to geologists minerals are naturally occurring organic solids that have a crystalline structure and a distinct chemical composition. 2. The Elements Group includes over two hundred known minerals. 3. Only one of sulfide minerals has a special importance as a rock-making mineral, it’s mercury. 4. All carbonates are not soft and brittle. 5. Phosphates are usually brittle and occur in small crystals or compact aggregates.
4. Say:
- the most common elements making up the minerals found in the Earth's rocks.
- what organic minerals are.
- which group of minerals is the largest one.
PART 2
Text 1
