While trying to determine this quantity for green tourmalines, C. J. Kerez observed multiple "shadow lines" instead of the normal number of two.
While trying to determine this quantity for green tourmalines, C. J. Kerez observed multiple "shadow lines" instead of the normal number of two. For two minerals, relative values of this property can be determined by ascertaining the direction of the Becke line, in a namesake test. In gemology, a device used to measure this property, developed by BJ Tully, uses a hemisphere of lead glass to rotate a sample. This value can be relatively ascertained by submerging an object into oil or some other liquid and searching for "reliefs" in the immersion method. Since it is dependent on density, this quantity is usually two or greater for resinous minerals. For a uniaxial crystal, this value for one crystal axis is different than it is for the other two crystal axes. For 10 points, name this property that is dependent on the polarization of light in a birefringent material, and which can be calculated with Snell's law.
While trying to determine this quantity for green tourmalines, C. J. Kerez observed multiple "shadow lines" instead of the normal number of two.
index of refraction [or refractive index; do not accept or prompt on "index" or "refraction"]