Most important aspects – density and refractive index
Hard, amorphous solidUsually transparentPrimarily composed of silica, with various amounts of elemental oxidesBrittleExhibits conchoidal fracture
Soda-lime—used in plate and window glass, glass containers, and electric lightbulbsSoda-lead—fine tableware and art objectsBorosilicate—heat-resistant, like PyrexSilica—used in chemical wareTempered—used in side windows of carsLaminated—used in the windshield of most cars
• Natural – slight green• Adding Manganese – clears it• Iron & sulfur – brown bottles• Chromium – green bottles• Cobalt – blue bottles• Copper – red bottles• Silver – yellow bottles• Tin – white bottles
Density—mass divided by volumeRefractive index (RI)—the measure of light bending due to a change in velocity when traveling from one medium to anotherFracturesColorThicknessFluorescenceMarkings—striations, dimples, etc.
Immersion method—lower fragments into liquids whose refractive index is differentMatch point—when the refractive index of the glass is equal to that of the liquidBecke line—a halo-like glow that appears around an object immersed in a liquid. It disappears when the refractive index of the liquid matches the refractive index of the object (the match point)
If Becke line is inside perimeter – the glass has a higher refractive index than the liquid If Becke line is outside perimeter – the glass has a lower refractive index than the liquid
Radial fracture radiate out from the origin of the impact begin on the opposite side of the forceRadial cracks form a right angle on the reverse side of the forceConcentric fracture circular lines around the point of impact begin on the same side as the force.
A high-velocity projectile always leaves a wider hole at the exit side of the glass.
Cracks terminate atintersections with others.can be used to determinethe order of events
Individual characteristics: if the fragments can fit together like pieces of a puzzle, the source can be considered unique