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Archive for March, 2008

Calcite

Monday, March 24th, 2008

The chemical formula of Calcite is indicated by CaCO3 or Calcium Carbonate. Calcite is a Carbonates mineral. It is commonly found having moderate negative to high positive relief and the change is marked during the rotation of the petrographic polarizing light microscope. Most of the Calcite minerals that are found forming particularly in the sedimentary […]

Anatase

Monday, March 24th, 2008

The chemical formula of Anatase is given by TiO2 or Titanium Oxide. Anatase like Brookite is known as a polymorph of Rutile. However, Anatase is considered rare mineral, while Rutile is the most common one. Rutile, Brookite, and Anatase have different structures but they have the same chemical composition indicated by the formula TiO2. Their […]

Borax

Monday, March 24th, 2008

The chemical formula of Borax is indicated by Na2B4O7-10H2O or Hydrated Sodium Borate. Borax is a Borate mineral. But then borate and nitrate minerals are all classified under Carbonate mineral class. This mineral commonly exhibits moderate negative relief when viewed under several adjustments on the aperture diaphragm of the petrographic polarizing light microscopes. Borax minerals […]

Alunite

Monday, March 24th, 2008

Mineral Alunite has the formula KAl3(SO4)2(OH)6 or Potassium Aluminum Sulfate Hydroxide. Alunite is one of the Sulfate minerals is also known as alum stone. This Sulfate mineral Alunite is a common source of the alum chemical. This mineral is most commonly formed in a process known as alunitization. In this process, the sulfuric acids act […]

Fluorite

Monday, March 24th, 2008

The chemical formula of Fluorite is indicated by the formula CaF2 or Calcium Fluoride. Fluorite is a Halide mineral. It commonly exhibits a moderately high negative relief when viewed closely under petrographic polarizing microscopes. Mineral Fluorite has a face-centered cubic structure. Fluorite is usually used as a flux in iron smelting. Fluorite is also a […]

Mineral Identification

Monday, March 24th, 2008

The mineral identification process is a systematic approach. May it be in thin section or grain mount, the process of identification should be tempered with the familiarity with variety of common rocks and minerals as well as with common sense in evaluation. It is also important to note that over 3000 different kinds of minerals […]

Opaque Minerals

Monday, March 24th, 2008

The identification of opaque minerals is sometimes done by shining a light on top of the surface of the sample. The opaque minerals can be identified by observing the color of the reflected light through the polarizing microscope. However, this method is not encouraged because it has been found that it has some drawbacks. This […]

Non-minerals

Monday, March 24th, 2008

There can be some instances wherein thin section sample are imperfectly prepared. This is most often the case with beginner mineralogists or students. Imperfectly prepared samples in thin section may possibly contain variety of materials that may be incorrectly recognized as mineral. The presence of the non-mineral materials can actually complicate the identification process. The […]

The Crystallographic Considerations on Uniaxial Minerals

Monday, March 24th, 2008

The geometrical shapes of uniaxial minerals usually include tetragonal or hexagonal. These uniaxial minerals possess a high degree of symmetry about the c crystallographic axis and this is the most common characteristic of these minerals. It can be also found that with the plane {001} or {0001}, there is uniform chemical bonding found in all […]

Optic Sign of Uniaxial Minerals

Monday, March 24th, 2008

The extraordinary ray of mineral calcite has lower index of refraction than it ordinary ray. But in some other minerals, the extraordinary ray may possibly have higher index. This property is most often used as bases for defining the optic sign of the mineral. If the index of the extraordinary ray is greater than index […]

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