Glass Forensics Vocabulary Flashcards
Becke line
Line created as refracted light becomes concentrated around the edges of the glass fragments
Density
The ratio of the mass of an object to its volume
Glass
A hard, amorphous, transparent material made by heating a mixture of sand and other additives
Leaded glass
Glass containing lead oxide
Obsidian
Volcanic glass
Refraction
The change in the direction of light as it changes speeds when moving from one substance to another
Refractive index
A measure of how light bends as it passes from one substance to another
Silicon Dioxide
The chemical name for silica
Amorphous
Without shaper or form
What 2 things that make glass different
The additives or the way it is manufactured to break
What is glass made out of
Silicon dioxide, soda lime and calcium oxide
How does glass have individual characteristics? Give an example
If the glass has blood or fingerprints on it
How does glass have class characteristics? Give an example
If you can tell what type of glass it is
Amorphous solid
A solid with molecules randomly arranged
What is a conchoidal fracture?
The curved fracture lines on the edge of radial or concentric cracks
What can conchoidal cracks help determine
Help determine which side of the glass the impact came from
What is the 3 R rule
Radial, right, reverse
What are 2 ways you can determine the direction of a bullet entering through glass?
- Using the 3 R rule on a piece of broken glass with a radial fracture edge
- or look at the hole left by the projectile
What are radial fractures
Fractures that radiate out from the central hole
What are concentric fractures
Fractures that form circles
What can radial fractures help determine
Order of hits and which side the glass is impacted
Where is the laminated glass found and what’s one property?
Windshield of car
Piece of plastic between 2 pieces of glass
Where is the lead crystal glass found and what’s one property?
Found in crystal glassware, or decorative glass art
-includes PbO to give it shine and weight
Where is the Pyrex glass found and what’s one property?
Baking pans, headlights
- resistant to rapid heat change
Where is the tempered glass found and what’s one property?
Cutting boards, car windows
- breaks into squares
Where is the soda lime glass found and what’s one property?
Windows, bottles
- can be recycled easily
