Answered: 1. Tourmaline has No=1.644 and…

Applications and Investigations in Earth Science (9th Edition)

9th Edition

ISBN:9780134746241

Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Chapter1: The Study Of Minerals

Section: Chapter Questions

Problem 1LR

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Question

Crystal Optics

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1. Tourmaline has No=1.644 and Ne=1.624. What is the axial lightness of tourmaline ()

A. One axis negative crystal

B. Biaxial normal crystal

C. One-axis normal crystal

D. Biaxial negative crystal

2. Corundum is a one-axis negative crystal. On the tangent plane of the oblique c-axis, the vibration direction of fast light is ()

A. Born

B. No

C. Born'

D. uncertain

3. Apatite (hexagonal crystal system), the polarized refractive index parallel to the c axis is 1.624, and the polarized refractive index perpendicular to the c axis is 1.629. The axial optical property of this mineral is ()

A. One-axis normal crystal

B. Biaxial normal crystal

C. Biaxial negative crystal

D. One axis negative crystal

4. The measured refractive index values on any three sections of a certain mineral are: ①1.544, 1.551; ②1.549, 1.544; ③1.553, 1.544; what is the axial optical property of this mineral ()

A. Biaxial negative crystal

B. One-axis normal crystal

C. One axis negative crystal

D. Biaxial normal crystal

5. The principal refractive index values on the (010) section of topaz (orrhombic mineral) are 1.607 and 1.617, respectively. The principal refractive index values on the (001) section are 1.607 and 1.610, respectively. The optical orientation of the mineral is ()

A. a∥Np，b∥Ng，c∥Nm

B. a∥Np，b∥Nm，c∥Ng

C. a∥Ng，b∥Nm，c∥Np

D. a∥Nm，b∥Np，c∥Ng

6. The refractive index of quartz is 1.544-1.553, and the protrusion level under the single polarizer is: ()

A. Median protrusion

B. Positive low protrusion

C. Protruding height

D. Negative low protrusion

7. It is known that No=1.658 and Ne=1.486 of calcite. What is the protrusion level of calcite perpendicular to the optical axis ()

A. Flash protrusion

B. Median protrusion

C. Protruding height

D. Negative low protrusion

8. It is known that No=1.658 and Ne=1.486 of calcite. What is the protrusion level of the calcite parallel to the optical axis ()

A. Median protrusion

B. Flash protrusion

C. Negative low protrusion

D. Protruding height

9. Biotite Ng≈Nm is dark brown, Np is light yellow, the main refractive index is known to be 1.697, 1.696, 1.616, Np∧c=3°, what is the axial lightness of biotite ()

A. One-axis normal crystal

B. Biaxial negative crystal

C. One axis negative crystal

D. Biaxial normal crystal

10. Biotite Ng≈Nm is dark brown, Np is light yellow, the main refractive index is known to be 1.697, 1.696, 1.616, and Np∧c=3°. What is the color and cleavage characteristics of biotite∥(001) section ()

A. Ng=dark brown, Np=light yellow, a group of extremely complete cleavage

B. Ng=dark brown, Nm=dark brown, a group of extremely complete cleavage

C. Nm=dark brown, Np=light yellow, a group of extremely complete cleavage

D. Ng=dark brown, Nm=dark brown, no cleavage

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