1. (Properties of Minerals)
Monday January 23, 2012
(Properties of Minerals)

2. The Launch Pad Monday, 1/23/12
This picture illustrates an example of calcite’s __________.
These pictures illustrate examples of pyrite’s __________.
cleavage
habit

3. Summative or Formative
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Summative or Formative
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Date Due
Date Into Grade Speed
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Launch Pads 1/4 - 1/6 F1
1/6
Project: Fossils S1
1/9
1/13
1/18
2/1
Lab – Fossils F4
1/12
Quiz 15 S2
1/17
1/31
Quiz 16 S3
1/20

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6. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Parting
Parting is a property that often gets confused with cleavage, and there is good reason for that. Parting is a break along structural planes and is parallel to a possible face, just like cleavage. However, parting differs from cleavage in some important ways. It can not be found in every specimen as is true of cleavage for most every cleavable mineral. It is not absolutely repeatable or reproducible as is cleavage down to theoretically the very atomic layers that cause cleavage.

7. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Specific Gravity
Specific Gravity is a measure of the density of a mineral. At times it is such a useful property that it is the only way to distinguish some minerals without laboratory or optical techniques.

8. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Specific Gravity
Gold an easily be distinguished from "fool's gold" by specific gravity alone Specific gravity is a unit-less measure, because it is derived from the density of the mineral divided by the density of water and thus all units cancel. However, since water's density equals 1 gram per cubic centimeter (at specific conditions), then a mineral's specific gravity would also correspond to a mineral's density as expressed in grams per cubic centimeter.

9. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Taste
Taste is not the first property someone would associate with minerals, yet taste is sometimes a very good characteristic and a key to identification in some cases. The most commonly "tasted" mineral is halite or rock salt, but there are several other minerals that have a distinctive taste.
NOTE: Consult your instructor or a professional before tasting a mineral – some are poisonous!
Examples: Borax (sweet alkaline), halcanthite (sweet metallic & slightly poisonous), Epsomite (bitter), Glauberite (bitter salty), Halite (salty), Hanksite (salty), Melanterite (sweet, astringent and metallic), Sylvite (bitter), Ulexite (alkaline)

10. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Smell
Several minerals give off a distinctive odor in certain conditions. Sulfur, in normal room conditions, gives off a mild odor resembling the smell of a lighting match. However if heated or struck, it gives off a powerful odor like rotten eggs. Arsenic gives off a very mild garlic smell in normal room conditions. However, if heated or struck, it gives off a powerful garlic odor. Although only few minerals have a characteristic odor, odor is very useful identification key.

11. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Tenacity
Tenacity is a mineral’s physical reaction to stress such as crushing, bending, breaking, or tearing.
Certain minerals react differently to each type of stress.
Since tenacity is composed of several reactions to various stresses, it is possible for a mineral to have more than one form of tenacity.
The different forms of tenacity are:

12. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Tenacity – Brittleness
If a mineral is hammered and the result is a powder or small crumbs, it is considered brittle.
Brittle minerals leave a fine powder if scratched, which is the way to test a mineral to see if it is brittle.
The majority of all minerals are brittle.
Minerals that are not brittle may be referred to as non-brittle minerals.

13. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Tenacity – Sectility
Sectile minerals can be separated with a knife into thin slices, much like wax.

14. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Tenacity – Malleability
If a mineral can be flattened by pounding with a hammer, it is malleable.
All true metals are malleable.

15. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Tenacity – Ductility
A mineral that can be stretched into a wire is ductile.
All true metals are ductile.

16. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Tenacity – Flexible but Inelastic 
Any mineral that can be bent, but remains in the new position after it is bent is flexible but inelastic.
If the term flexible is singularly used, it implies flexible but inelastic.

17. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Tenacity – Flexible and Elastic 
When flexible and elastic minerals are bent, they spring back to their original position.
All fibrous minerals, and some acicular minerals belong in this category.

18. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Elasticity
The elasticity of a mineral refers to the tendency of the mineral to return to its original shape after it has been stretched or compressed.

19. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Feel
The "feel" of a mineral can sometimes help identify it.
Some minerals are greasy to the touch, others are smooth, and others have a rough feel.
Diamond, which absorbs heat better than any substance, has a unique, cold feel at room temperature.
talc
greasy
fluorite
smooth
feldspar
rough

20. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Feel
Some specimens of a particular mineral may have a rough feel since they are composed of tiny, protruding crystals, while other specimens of the same mineral have a smooth texture.
Therefore, a rough feel is not necessarily an identification factor.
A greasy and smooth feel, however, are inherent to all specimens of the same mineral.
Fibrous minerals have a distinct, silky feel.

21. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Magnetism
Several minerals react when placed within a magnetic field. Some minerals are strongly attracted to the magnet, others are weakly attracted, and one mineral is repelled. There are also several minerals that are attracted to magnetic fields only when heated.
The presence of iron in a mineral is responsible for the magnetic properties of minerals in virtually all cases.

22. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Double Refraction
Double refraction is a phenomenon exhibited on all non-opaque minerals except for amorphous ones and ones that crystallize in the isometric system.
A light ray enters the crystal and splits up into two separate rays, making anything observed through the crystal appear as double.

23. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Double Refraction
In some minerals, such as the Iceland Spar variety of Calcite, double refraction is strongly seen.
The double refraction is different in every mineral, and thus can be used to identify gems.
Double refraction is measured with a refractometer.

24. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Reaction to Hydrochloric Acid
An important property in minerals is how they react to acids.
All of the minerals that have some reaction to acids tend to be carbonates and a few other minerals that contain significant amounts of carbonate ions.
Carbon dioxide gas is given off.
The bubbles or effervescence is the reaction we are looking for and indicates the presence of carbonate ions.

25. Minerals - The Building Blocks of Rocks
Physical properties of minerals
Reaction to hydrochloric acid
With calcite and aragonite, the two most common carbonate minerals, the reaction to a cold, dilute acid is easily accomplished and is often so energetic that it is associated with a fizzing noise.

26. The Rock-Forming Minerals
The eight elements that compose most rock-forming minerals are oxygen (O), silicon (Si), aluminum (Al), iron (Fe), calcium (Ca), sodium (Na), potassium (K), and magnesium (Mg).
The most abundant atoms in Earth’s crust are oxygen (46.6% by weight) and silicon (27.7% by weight)
Composition of the Continental Crust