Transmitted 20 Degrees Off Crossed Linear Polarized Light
Significance in the Environment:
This is a common clothing fiber.
Flax has a refractive index along its length of about 1.58 to 1.60 and perpendicular to its length of about 1.52 to 1.53.
It has a birefringence of up to 0.06 and a positive sign of elongation.
DuPont Company Techinical Bulletin X-156: IDENTIFICATION OF FIBERS IN TEXTILE MATERIALS, December 1961.