MINERALS. Characteristics and Properties. What is a mineral? Naturally occuring Not man-made (synthetic) or biologically produced. Pearls, styrofoam, charcoal are not minerals Inorganic Not formed from processes involving organisms (living or once living) Solid
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Characteristics and Properties
Not man-made (synthetic) or biologically produced.
Pearls, styrofoam, charcoal are not minerals
Not formed from processes involving organisms (living or once living)
Has definite chemical composition
An element or compound
Has an orderly arrangement of atoms
Crystalline structure-that is-atoms have repetitive patterns and internal structures are distinct.
Geometric solids with smooth surfaces (crystal faces)
Identifying Characteristics of Minerals
Color by itself IS NOT sufficient to identify a mineral
How the material reflects light
Metallic-shiny. Ex: silver, copper, etc
Nonmetallic-Pearly or cloudy, dull
How easily the mineral can be scratched
Can be compared to the hardness of other minerals by using the Mohs scale
The powder form of the mineral left on a porcelain plate (must be softer than the porcelain)
The way the mineral splits along flat surfaces
Determined by the arrangement of the atoms
Not all minerals have cleavage
Ratio of mass to volume
Determined by the mass of the atoms and how close they areMineral Characteristics
One way is the cooling of magma
Thermal energy is lost; atoms migrate together and form different compounds
The elements present and the amounts determine the kind of minerals
Different crystal structures are formed
If the magma cools slowly, large crystals are formed. Different minerals form at different temperatures. Heavier minerals such as magnetite sink and lighter ones float.
Minerals such as quartz and calcite form late in the cooling process and are known as hydrothermal minerals. In the last few years, hydrothermal vents have been formed on the ocean floor. In these areas, sea water filters into the hot crust and is heated to 400 degrees C. The hot water then reacts with the crust and becomes a metal bearing liquid. When it returns to the cooler sea floor, it deposits minerals, including iron, copper and zinc sulfide.
--Minerals can precipitate out of a solution
When water is saturated with dissolved solids and can’t hold any more, the excess falls out of the solution. An example of this is the manganese nodules on the ocean floor
--Minerals can form by evaporation
Minerals such as salt, gypsum and calcite (calcite forms in two ways) are formed from sea water when it evaporates. This happens in warmer parts of the world where the sun's heat evaporates the water and leaves the minerals.
Other ways that minerals are formed:
Some minerals are formed from the weathering of rocks.
Chemical changes are caused by atmospheric oxygen, water and acid rain. Such action can change feldspars to kaolin and pyrite (fools gold) into a brown iron ore called limonite
And lastly some minerals are formed when rocks are metamorphosed, that is subjected to heat and pressure.
Minerals formed in this way include garnet and mica.Formation of Minerals
glassy (vitreous), silky