lab 2 key terms

Question 1

relief

Answer 1

how prominent its outline is on the surface
high, medium, and low

Question 2

refractive index (RI)

Answer 2

determined by a becke line test
lines move toward the medium with the greater RI

Question 3

pleochroism

Answer 3

how the transmitted light colours of some minerals vary from strong to weak as the stage is rotated.
The colours you see are wavelengths reflected or transmitted
The colour changes as the stage is rotated because the orientation of the grain changes.

Question 4

opaque minerals

Answer 4

do not transmit light in thin section and appear black under PPL and XPL

Question 5

isotropic minerals

Answer 5

same properties in all directions
transmit light under PPL but remain black under XPL as the stage is rotated