Rocks and Minerals

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  • Topic: Mineral, Mohs scale of mineral hardness, Chlorine
  • Pages : 4 (885 words )
  • Download(s) : 94
  • Published : December 17, 2012
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All minerals have four properties:

1. All minerals are naturally occurring

2. All minerals are inorganic (that means non-living)

3. A different chemical formula can be written for each mineral and that formula is constant for that mineral.

ex. Galena is PbS- that is it has one lead atom (Pb) and one sulfur (S) atom in each molecule.

4. Most minerals have an unique crystalline shape given the right growing conditions (like in a cave).

Compounds are substances that has two or more elements chemically combined. When the compound is formed, it has different properties than the elements it is made from.

For example, NaCl is a substance made from Na- Sodium and Cl- Chlorine. Sodium explodes when it is combined with water, and chlorine is a poison. When these elements are combined, they form NaCl, what we call table salt (halite).

Identifying Minerals

Minerals have many different properties, and geologists use these properties to determine what kind of mineral is before them. Scientists use a combination of properties to distinguish between these minerals, using the process of elimination. More on the physical properties of minerals. The following is a description of each of these properties:

1.Color-

Color is usually the first property observed when handling a specimen. Color alone is not reliable, but it can help us to eliminate possibilities. We must be sure we have a freshly exposed surface, because weathering can change the color of a mineral. Some minerals, such as sulfur, always have the same color(yellow). Other minerals may have different colors. One example is quartz, which may be clear, purple, pink and even gray!

2.Luster-

Luster is the way light reflects from a mineral's surface. Luster is either metallic or nonmetallic. Metallic minerals look like.... well, a metal. Nonmetallic minerals can be glassy, dull, brilliant, waxy, earthy, or pearly.

3. Streak-

The color of the powder of a...
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