Mineral is any naturally occurring, inorganic, crystalline substance
(element or compound) that possesses a fairly definite chemical composition
and a distinctive set of physical properties. Minerals are composed
for the most part, of eight elements. They are found in the earth's
crust which is a thin shell of thickness ranging from 4.8 km (3 miles)
to 48 km (30 miles). Oxygen and Silicon are the two most common elements
comprising 74% of the crust. The table below gives the Relative percentages
of the elements in the Earth's crust.
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| Oxygen (O) | 46.5 |
| Silicon (Si) | 27.5 |
| Aluminum (Al) | 8.1 |
| Iron (Fe) | 5.3 |
| Calcium (Ca) | 4.0 |
| Magnesium (Mg) | 2.7 |
| Sodium (Na) | 2.4 |
| Potassium (K) | 1.9 |
| All Others | 1.6 |
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Properties of Minerals.
1. Crystal habit (shape) is the size and shape assumed by the crystal faces when a crystal has time and space to grow. It is the result of the interaction of the atomic structure with the environment. All crystalline substances crystallize into one of seven major geometrical patterns. For more details click below:
2. Hardness is comparative and refers to the ability of a mineral to scratch or resist scratching by other minerals. Moh's scale of hardness groups the minerals from 1 to 10 according to hardness (1 = softest, 10 = hardest). A mineral with a higher number will scratch one with a lower number. For more information click below
3. Cleavage refers to the tendency of some minerals to break along definite smooth planes. A mineral may have no distinct cleavage or may have on or more distinct planes.
4. Color is the property of reflecting light of one or more wavelengths. It is unreliable as identification as the presence of even small amounts of impurities can change the color.
5. Streak refers to the color of the powder when rubbed against the surface of unglazed porcelain. A mineral has the same streak irrespective of its color.
6. Luster is the appearance of the mineral's surface in reflected light. They may appear metallic or nonmetallic.
7. Fracture refers to the manner in which a mineral breaks. It may break into splinters, ragged or rough irregularly shaped pieces, or shell-shaped forms known as Conchoidal fractures.
8. Tenacity is the ability of the mineral to hold together. They may be tough and durable or fragile and brittle.
9. Magnetism is the property of possessing a magnetic force field. It can be detected by a magnetic compass.
10. Fluorescence refers to the emission of visible light by a mineral that is being stimulated by the absorption of ultraviolet or X-ray radiation. For more information click below
11. Phosphorescence refers to the emission of light by a mineral after the stimulating source (light or ultraviolet radiation) has been removed. For more information click below
For details of all the properties in a slide show, click below.
For more information about minerals, Click below:
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