Forensic Geology and

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Forensic Geology and Industrial Materials
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Building Materials

• Building materials are made of or derived
• from geological materials
• Stone, gravel, sand, slate, etc.
• Roofing granules
• Bricks, roof and floor tiles
• Cement, concrete, cinder blocks
• Wallboard, plaster
• Glass
• Cleansing powders, abrasives
• Insulation

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Brick Making
The basic process Find a suitable clay
Press it into a brick mold Dry the bricks
Fire the bricks to 1000C
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Cement Manufacture

• Cement is made by mixing limestone, sand, clay,
  and sometimes coal fly ash, with minor amounts of
  iron and aluminum compounds
• Mixture is fired in a kiln to 1500C where the
  limestone is calcined into lime which reacts with
  the silicates to form di-and tri calcium
  silicates, and tri-
• and tetra calcium aluminates

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Cement Manufacturing Process
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Concrete Manufacture

• Concrete is made by mixing cement with sand,
  gravel, and water.
• Cement slurry coats the aggregate and hardens
  into a solid mix.

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Cinder Blocks -manufactured by mixing cement
with coal fly-ash. NOTE many industrial
materials are manufactured close to end-users
using local materials.
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Plaster Manufacture

• Plaster is made by calcining gypsum CaSO4 2H2O
  at 150ºC to its hemi-hydrate CaSO4 ½H2O
• This is an ancient process again going back to
  the beginning of civilization.

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• After the great fire of London in 1666, the King
  of France ordered that all of the wooden
  structures be coated with plaster to make them
  fire resistant.
• Modern processing adds various additives, filler,
  conditioners with the result that most plasters
  can be differentiated from each other.

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• 88 of the gypsum mined is used in the
  manufacture of wallboard.

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Abrasives

• Abrasive materials are used in a variety of ways
  sanding wood, polishing diamonds, cutting steel.
• Diamonds are the hardest abrasives.
• Corundum, garnet, SiC, cubic boron nitride, Zi/Al
  alloys, pumice, and colloidal silica are also
  used.

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Pumice
Diamond
Silicon Carbide
Garnet
Corundum
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The Role of the Forensic Geologist

• Industrial materials have textural and
  compositional properties suited to petrographic,
  chemical, x-ray diffraction (except for glass),
  and spectral analytical methods familiar to
  geologists
• Geologists are ideally suited to perform such a
  variety of analysis.

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Building Materials Cases

• An attempted rape case
• -the rescuer of the victim was followed by
  the suspect, beaten with an aluminum baseball
  bat, and the windows of his car were smashed out.
• Glass adhering to the suspects bat matched glass
  from the rescuers car
• (Murray, 2004, page 101)

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• Case a home owner who had insulated his attic
  with a variety of fiber glass insulation
  purchased from different sources.
• An intruder who entered through the attic was
  found to have a similar variety of insulation
  particles on his clothes (Murray, 2004, page 103)
  

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• Diplomatic case the neutral Dutch were accused
  by British in WWI of allowing the Germans to ship
  sand and gravel through Holland.
• British geologist, Capt. W. B. R. King, took 39
  samples of concrete aggregate from captured
  German pillboxes.
• -found that 32 of them came from German not
  Dutch sources
• (Murray, 2004, page 107)

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• A case in Israel
• - a safe cracker stole a safe tried to cut
  into it using a carbide grinding wheel with two
  different abrasive discs.
• Investigators recovered the grinder and were able
  to match the grinder to the grinding marks on the
  safe.
• -also matched metal particles found on the
  suspects shirts to the grinding debris at the
  scene.
• (Zeichner et al., 1993, J. For. Sci., p.
  1516-1522)

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Wood Identification

• Wood is not generally considered a geological
  material however, wood properties and
  characteristics have been used in forensic cases.

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Elm Wood Under the Hand Lens
Elm Wood Under the Microscope
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Hardwood (Sugar Maple) with Large Pores
Softwood (Sequoia) with Large Pores
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The Lindbergh Kidnapping Case

• In 1932, the infant son of aviator Charles
  Lindbergh was kidnapped and later found dead.
• A major piece of evidence, a home-made ladder
  found at the scene, was found to match the
  boards in the attic of the suspect Bruno
  Hauptmann
• Hauptmann was convicted and executed in 1936
  

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Sarsaparilla Case

• DEA agents asked a wood expert to examine some
  roots that they thought were illicit drugs.
• -the suspect said plants were sassafras.
• Examination revealed that they were the roots of
  the sarsaparilla plant and the case was dropped
• (Science News Online, 2002,
• v. 162)