Schreger Lines
Definition
Crossing arc patterns in elephant and mammoth tusk cross-sections formed by the angles at which dentinal tubule bundles intersect. The acute angle at the crossing point distinguishes elephant ivory (under 115 degrees) from mammoth ivory (over 115 degrees).
- Location
- Tusk cross-section (dentine)
- Cause
- Angle of dentinal tubule bundle intersection
- Elephant angle
- Over 115 degrees
- Mammoth angle
- Under 115 degrees
Common questions
Why does the Schreger angle matter for ivory identification?+
Legal mammoth ivory trade is permitted in some jurisdictions because mammoths are extinct and not covered by CITES, so distinguishing mammoth from elephant ivory by Schreger angle helps determine whether a piece can legally be sold.
Can Schreger angle measurement be fooled by carving or aging?+
Heavy carving, polishing, or surface treatment can obscure or distort the visible cross-section pattern, which is why examiners look for an intact cut surface and may combine the angle measurement with other tests when the ivory has been worked.
Related terms
- Dentinal Tubules
- Microscopic channels running radially through dentine from the pulp cavity to the outer surface. They house odontoblast cell processes that can carry...
- Mammoth Ivory Legality Gap
- Because Mammuthus primigenius is extinct and therefore not within CITES scope, its ivory is not internationally regulated. This legal gap is exploited...
- Pulp Cavity
- The hollow channel inside a tusk or tooth that in life contains blood vessels and nerves. In elephant tusks the pulp cavity...
- Rhinoceros Horn Keratin Tubules
- Tightly packed melanin-pigmented keratin fibres, 50-80 micrometres in diameter, visible in a rhino horn cross-section under SEM. Distinguished from the keratinous sheath...
- Schreger Angle
- The acute angle formed at the intersection of two sets of dentinal tubule lines visible in the cross-section of a tusk. Values...