Each layer of the Earth has a different density
Thickness of each layer:
Lithosphere: outer portion of the crust
Rock formers: 9 abundant elements in the litosphere
Common elements that make up the minerals of the crust, in decreasing abundance:
Organic: Once living; ex: coral, mollusk, shells
Inorganic: Never living
We can observe the internal atomic pattern by use of X-ray defraction.
If the arrangement of the molecules is large enough to be recognized by the eye, we call it a Crystal.
Large crystals are uncommon because when crystals start to form they interfere with each other. Instead of growing into large recognizable crystals, the crystals grow together -- the mineral is said to be massive.
Mineralogist: a scientist who studies minerals.
Si + O -- largest group; 87% of the crust
C + O
To test for a carbonate, place a drop of HCl (hydrochloric acid) on the sample. If it fizzes, it's a carbonate.
O2 + some other element, e.g. Fe2O3
Tetrahedron structure: basic unit of all silicates
Silica is SiO4. The atoms are arranged with Si in the center:
Crystal faces: the flat surfaces which join at well defined angles.
The angle between crystal faces is always the same, regardless of size.
Luster: the wasy that it reflects light
Non-metallic luster terms:
Streak: the color of the powdered mineral
Rub the mineral on a porcelain plate. The color that comes off the mineral is called the streak color.
Hardness: resistance to being scratched
|Mohs Scale||Field Test|
|1. Talc||Soft, feels greasy|
|2. Gypsum||Scratched by fingernail|
|3. Calcite||Scratched by a penny|
|4. Fluorite||Easily scratched by a knife blade|
|5. Apatite||Scratched by a knife blade with difficulty|
|6. Feldspar||Scratched by glass|
|7. Quartz||Will scratch glass|
|8. Topaz||Scratches quartz|
|9. Corundum||Scratches topaz|
|10. Diamond||Scratches corundum|
Shape: external appearance
Some terms that can be used for minerals that have a definite shape:
The ratio of the weight of a mineral to the weight of an equal volume of water.
Specific gravity tells you how many times as heave as water the mineral is
Specific Gravity = (weight in air) / (loss of weight in water)
The outward color, NOT streak color
Color is usually not an important quality
Some minerals vary in color; e.g. quartz can be: clear, white, pink, purple, smokey.
Many minerals have the same colors or similar colors; e.g. fluorite and quartz can both be purple.
The ease with which light will pass through it.