This is a sample yak hair from the sample-set provided by Textile Fabric Consultants, Inc.
Transmitted 20 Degrees Off Crossed Linear Polarized Light
Significance in the Environment:
Yak hair has a refractive index along its length of about 1.56 and perpendicular to its length of about 1.55.
It has a birefringence of about 0.01 and a positive sign of elongation.