Anisotropic_Minerals

Anisotropic_Minerals - Isotropic Minerals Easily identified...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Isotropic Minerals • Easily identified - Always extinct with upper polarizer inserted - vibration direction not changed by material - all light blocked by upper polarizer • Anisotropic usually (but not always) light with color • Measuring n important diagnostic tool - Not completely diagnostic, may vary & more than one mineral with same n - Can’t be done in thin sections • Can use other optical properties for ID, e.g. texture - color (but variable) - cleavage (may not see, control shape) - shape (depends on cut of mineral) Anisotropic Minerals • Show property called Double Refraction - light entering material usually split into two rays - depends on direction light passes through material - two rays vibrate at 90º to each other • Value of n is determined by vibration direction - one direction n larger than other. - direction with large n is slow ray - direction with small n is fast ray 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Optic Axis - special direction where rays not split into two rays - hexagonal and tetragonal have one optic axis - uniaxial - orthorhombic, monoclinic, and triclinic have two optic axes – biaxial Interference Phenomena • in most cases, some light passes the analyzer - specific color is interference color - caused by two rays resolving to one when they leave mineral Interference with monochromatic light • Light split into fast and slow ray - fast ray travels farther than slow ray in same time - difference in the distances called retardation, - retardation remains same after two rays leave mineral (air is isotropic) • Retardation depends on thickness (d) and the difference in n
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/06/2011 for the course GLY 5245 taught by Professor Staff during the Spring '11 term at University of Florida.

Page1 / 7

Anisotropic_Minerals - Isotropic Minerals Easily identified...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online