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Soils and Glass are know as:
- Primarily mineral in content
- Generally viewed as class evidence
- Usually analyzed by forensic chemist, and more rarely by mineralogist.
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What are the two natural soils?
- Organic- decayed and decaying vegatative & animal matter
- -often called "Humus"
- Inorganic-Crushed rock and clay material
- -minerals containing metal & non-metal ions
- -2,000 minerals (50 in the US)
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What are the interactions of five soil forming factors
- Time- crime and knows collected, distribution may have occured.
- Climate-helps trap the soil better because of the moist and soil color is affected.
- Parent material- material that wasl already on the shoe
- Topography-Study of the earths surface
- Plant & animal life-How they affect the soil.
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GLASS:
Has properties of both solid an liquid
- Made of oxides of melted silicon (sand) plus other additives, which are cooled without crystallizing
- -metal oxides (sodium, calcium, magnesium, and aluminum)
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What does sodium do to GLASS?
Sodium carbonate (soda) lowers the melting point
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What does calcium oxide do to gas?
Calcium oxide (lime) prevents glass from disolving
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Name the physical properties of GLASS:
- Weight
- Volume
- Color
- Boiling point
- Melting Point
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How to light waves work in relations to GLASS?
They travel in air at constant velocity until they penetrate another medium, such as glass or water, at whch point they are suddenly slowed, causing the rays to bend
Refration: bending of light waves due to change in velocity
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What types of Glass are there?
Tempered GLASS- when glass is heated and then cooled fast. (if glass breaks it will shatter into small pieces)
- Laminated GLASS- consist of two layers [plastic and glass]
- -ex: windshield
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Glass comparison
-Two important physical properties (also knows as test that can be performed on glass)
Density- D=M/V
Refraction index- when light passes through a transparent mean (works better in solids)
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What is Fracture Patter Analysis?
Individualizing a piece of glass to a particular object
- -point of entrance and beveled in
- -point of exit from medium is irregular and wider
- -sequence of impact determination:
- *fracture terminate at an existing line of fracture
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