5. Agate and milky quartz are both quartz, because they have the
same chemical composition and therefore, physical properties.
The differences between them are caused by impurities, other
chemical elements that are included in the quartz during the
formation process.
6.
7.
8.
9. NATIVE
ELEMENTS
These minerals are made by
a single element.
Gold, silver,
copper
OXIDES They are made up of
Oxygen and one other
element.
Oligiste (iron)
SULPHIDES A mix of Sulphur and a Metal Galena
CARBONATES They are made of Carbon,
Oxygen and a Metal.
Calcite
HALIDES Composed of Chloride and a
Metal.
Halite
10. a) COLOUR: minerals are always the same colour, no matter where
they are taken or what process endured.
b) SHAPE: minerals can be geometric or irregular.
c) LUSTRE: refers to the way a mineral reflects ligt. It can be:
- Metallic: like pyrite.
- Non metallic.
d) STREAK: it refers to the colour of the powder that a mineral leaves
when scraped.
e) CLEAVAGE: is the way a that a mineral breaks. It can break in
sheets or in cubes.
f) HARDNESS: measures how a mineral reacts to being scratched.