Science Focus Topic 1 Notes: Minerals
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Rocks contain naturally occuring, non-living minerals. Most minerals are rare and can be elements (pure substances) or compounds (combinations of pure substances). Minerals are not only found in rocks, but they are also found in your
Moh's Hardness Scale
- Friedrich Mohs developed a scale with 10 values of 'hardness' in 1812 (see Table 5.1 p. 355)
- Diamond is the hardest and talc is the softest (check the table to find out how hard common objects, like your
- Crystals are the building blocks of minerals. They occur naturally, having straight edges,
flat sides and straight angles.
- There are 6 different crystal types: cubic, tetragonal, hexagonal, orthohombic, monoclinic and triclinic (Table
5.2 p. 355)
Identification of Minerals
The properties that can be used to identify minerals are:
- Lustre: this refers to the 'shininess' of the mineral (how
light is reflected off the surface)
- Colour: colour can vary even within the same mineral, like
corundum (it can be white, blue or red), depending on what other elements are present.
- Streak: a streak is the color, of the powdered form, of the
mineral. (it can be made by scratching a porcelain tile)
- Cleavage and Fracture: is the way a mineral breaks apart.
If it breaks along smooth, flat surfaces or planes, it has cleavage. If it breaks with rough or jagged edges, it
- Transparency: it can be transparent
(see through), translucent (shadowy),
opaque (non-see through).
- Iron and pyrite help the blood carry oxygen
- Kidneys produce crystals, called kidney stones
- Calcium and dolomite help regulate water in body cells
- Diamonds are used in surgery, razor blades, computers, dentistry, oil drilling and a glass-cutter's wheel has
diamonds embedded in it.