Optical Properties

Question 1

display simultaneously the maximum and minimum refractive indices.

Answer 1

Birefringence

Question 2

This maximum colour is often diagnostic of an anisotropic mineral

Answer 2

Birefringence

Question 3

For anisotropic minerals only. It is observed w/ reference to the color chart (Michel – Levy Chart)

Answer 3

Interference colors

Question 4

The term used in describing interference colors.

Answer 4

Order

Question 5

Those w/ uniform physical properties in all directions. It remain dark in all positions even if the stage is rotated.

Answer 5

Isotropism

Question 6

Those that display colors in varying degrees as the stage is rotated. It produces interference colors.

Answer 6

Anisotropism

Question 7

band or rim of light visible along a grain/crystal boundary in plane-polarized light.

Answer 7

Becke line

Question 8

the ratio of the velocity of light in a vacuum to its velocity in the medium

Answer 8

Refractive index

Question 9

degree of visibility of a transparent mineral in an immersion medium

Answer 9

Relief

Question 10

Canada balsam is equal to

Answer 10

1.53

Question 11

Grains that show no recognizable crystal form

Answer 11

Anhedral

Question 12

Grains that show imperfect but recognizable crystal

Answer 12

Subhedral

Question 13

Grains that show sharp and clear crystal form

Answer 13

Euhedral

Question 14

the ability of a mineral to separate into smaller particles bounded of faces of possible crystal form

Answer 14

Cleavage

Question 15

observed w/ plane prolonged light; not always the same as megacopic color

Answer 15

Color

Question 16

change in color of a mineral in varying degrees as the stage is rotated due to differences in light absorption

Answer 16

Pleochroism