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The texture of rocks
WORK AND EXPERIMENTATION TECHNIQUES
1.
Which of the observed rocks is homogeneous? How did you know?
2.
What are the main differences between conglomerates and sandstone?
3.
What type of igneous rocks are granite and basalt? Can you observe any differences in their textures?
4.
Based on the results of this science practical, define in your own words the different types of rocks (igneous,
sedimentary and metamorphic).
5.
Which of the rocks observed were formed in the exterior of the Earth’s crust? And in the interior?
1.
Put each rock, one by one, on the slide of the binocular loupe. Look through the eyepieces
and move the macrometric screw until the rock is sharply focused.
2.
Observe each rock and draw what you see for each rock.
3.
Place a ruler next to the rock and, with the help of the loupe, measure the crystals
or fragments that compose the rock.
4.
Do another drawing of each rock observed.
Procedure
Some characteristics of rocks cannot be seen by just looking at
them. In this science practical, you will learn to use a binocular
loupe to compare different rocks and distinguish them
according to texture.
Materials
❚
Binocular loupe
❚
Five different rocks, for example,
conglomerate, sandstone, basalt,
granite and gneiss
❚
Ruler
Texture of conglomerate
Texture of gneiss
Texture of sandstone
To analyse the results and compare the rocks, use the following table next to your drawings:
Analysis of results
Name of rock
Minerals it is
composed of
Size of the
components
Type of rock
...
...
...
...
