Main Elements in the Continental Crust

Date: 2015-10-07; view: 480.

Minerals

PART 1

INFORMATIVE READING- Minerals and their physical properties.

Table 2. Chemical Grouping and Composition of Some Common Minerals

3.1.3 Complete the following chart. Give examples of each type of rock forming mineral.

3.2.1 Read the following text and answer the questions.(R.P – 4.7)

Minerals are the fundamental building blocks of rock materials in the earth. They are defined as naturally occurring inorganic substances with a definite chemical composition and specific crystal structure. Over 2000 minerals have been identified in the Earth. There are over 100 elements in the crust, which consists almost entirely of eight elements. The remaining elements account for less than 1% of the crust, which therefore has a very simple composition.

The first eight elements are the most common and constitute the basic ingredients for most continental crustal rocks, which are predominantly are silicates and to a lesser extent oxides.

As minerals are defined by composition and by crystal structure, these two parameters must be consistent to result in the predictable constancy of each mineral. Crystal structure is controlled by composition that directly determines the arrangement of atoms. Some minerals can occur in several polymorphs (physical forms), so some of the physical properties expected for one particular polymorph will not apply to another form. At the same time, some physical characteristics have a sufficiently wide range may be non-diagnostic by themselves, but will be indicative when combined with other features.

(General Geology. Textbook. Part 1-Tomsk: TPU Press, 2004)

1. What are minerals?

2. How many minerals are in the earth?

3. What are the main elements in the continental crust? Enumerate them.

4. What are the two parameters of minerals?

5. What is the main characteristic feature of crystal structure?