Diagnostic Test Questions 1-50

Question 1

A thin section analysis of an igneous rock reveals the following modal mineral percentages: Q = 35%, A = 25%, P = 30%, M = 10%. What is the normalized QAPF percentage for Q?

Answer 1

0.3889

Question 2

The Becke Line is a bright halo around a mineral grain observed when the microscope focus is slightly changed. It is used to determine the _____ of a mineral grain.

Answer 2

Relief

Question 3

The following minerals are generally idiochromatic, except: a. cinnabar b. azurite c. orthoclase d. almandine

Answer 3

Orthoclase

Question 4

The metamorphic facies characterized by the assemblage heulandite + analcite + quartz ± clay minerals in meta-igneous rocks and greywackes.

Answer 4

Zeolite

Question 5

Troctolite is a relative of gabbro that is ________.

Answer 5

Olivine-rich

Question 6

Which of the following minerals is NOT pleochroic? a. tourmaline b. spodumene c. zoisite d. Feldspar

Answer 6

Feldspar

Question 7

A volcanic rock with 53% wt SiO2 and 4 wt% (Na2O + K2O) would be classified as what on the TAS Diagram?

Answer 7

Basaltic Andesite

Question 8

Undulatory extinction is common in which minerals? A. garnet B. olivine C. Hornblende D. Quartz

Answer 8

Quartz

Question 9

Dessert rose is a common name for which mineral, known for its rosette-like crystal formation?

Answer 9

Gypsum

Question 10

The boundary line between (liquid) and (liquid+solid) regions of phase diagram is known as:

Answer 10

Liquidus

Question 11

These are dark bands that form a cross or curve pattern within the interference figure.

Answer 11

Isogyres

Question 12

Adularia is a low-temperature variety of:

Answer 12

Orthoclase

Question 13

A rock containing 45% olivine, 50% orthopyroxene, and 5% clinopyroxene would be classified as:

Answer 13

Harzburgite

Question 14

A mineral with a grape-like or globular form is said to have a _____ habit.

Answer 14

Botryoidal

Question 15

An intrusive igneous rock composed predominantly of calcium-rich plagioclase feldspar.

Answer 15

Anorthosite

Question 16

An iridescent schiller in Labradorite is due to the presence of a ______, causing exsolution of orthoclase from the plagioclase host during cooling.

Answer 16

Miscibility Gap

Question 17

The plagioclase feldspar series represents a ____ solid solution.

Answer 17

Continuous

Question 18

Which of the following can be a protolith of amphibolite? A. Peridotite B. Gabbro C. Sandstone D. Slate

Answer 18

Gabbro

Question 19

What is the size range of sand particles in mm?

Answer 19

1/16 to 2 mm

Question 20

An intrusive igneous rock contains 15% nepheline, 25% alkali feldspar, 51% plagioclase, 4% biotite, and 5% hornblende. You would name this rock as: a. Nepheline-bearing syenite B. nepheline monzosyenite C. nepholinite D. Nepheline monzogabbro

Answer 20

Nepheline-bearing syenite

Question 21

A plane parallel to the a-axis and intercepting the b-axis at 1 and the c-axis at 1 has Miller indices: A. (011) B. (101) C. (110) D. (001)

Answer 21

11

Question 22

Which mineral often displays a distinctive “Berlin blue” interference color in thin section when viewed under x-polars? A. biotite mica B. Calcite C. Quartz D. Kyanite

Answer 22

Kyanite

Question 23

Bird’s eye extinction is commonly observed in: a. Pyroxene b. Biotite c. quartz d. olivine

Answer 23

Pyroxene

Question 24

A crystal form consisting of two parallel and opposite faces. A. Pedion B. Pinacoid C. Dome D. Aphenoid

Answer 24

Pinacoid

Question 25

Which is NOT a variety of beryl? A. Heliodor B. Emerald C. Alexandrenite D. Morganite

Answer 25

Alexandrite

Question 26

The following minerals are radioactive except: A. Autonite B. Carnotite C. Thorianite D. None of the above

Answer 26

None of the above

Question 27

A _____ is the smallest building block of a crystal and is a representative unit of the repetitive ____ in the crystal structure.

Answer 27

Unit Cell; Lattice

Question 28

Which of the following is NOT a type of allochem used in Folk Classification? A. Intraclast B. Ooids C. Peloids D. Sparite

Answer 28

Sparite

Question 29

A copper antimony sulfosalt.

Answer 29

Tetrahedrite

Question 30

On a phase diagram, a eutectic point indicates which of the following? A. Both compounds are solid B. The melting point of the mixture is lower than the melting points of either of the individual compounds. C. One compound is in the liquid phase whilst the other is in the solid phase. D. It always occurs when the ratio of compound A to B is 50:50

Answer 30

B

Question 31

The blue variety of beryl is: A. Sapphire B. Emerald C. Morganite D. Aquamarine

Answer 31

Aquamarine

Question 32

A chiastolite mineral with a cross-shaped inclusion pattern. A. Staurolite B. Kyanite C. Sillimanite D. Andalusite

Answer 32

Andalusite

Question 33

In plagioclase feldspars, most common twin law is: A. Carlsbad twin law B. Albite twin law C. Pericline twin law D. Baveno twin law

Answer 33

Albite Twin Law

Question 34

How many distinct Bravais lattices are there?

Answer 34

14

Question 35

Which of the following mineral is NOT birefringent? A. quartz B. Calcite C. Olivine D. Spinel

Answer 35

Spinel

Question 36

A specific type of contact twinning found in quartz, where the c-axis of one crystal is inclined at an angle of 84 degrees 33 minutes to the other.

Answer 36

Brazil Law

Question 37

A sandstone with a high proportion of feldspar is classified as:

Answer 37

Arkose

Question 38

A ternary diagram used to distinguish the calc-alkaline magma series from the tholeiitic magma series.

Answer 38

AFM

Question 39

This is a rock that is transitional between metamorphic and igneous rock, formed when partial melting occurs during high-grade metamorphism.

Answer 39

Migmatite

Question 40

What is the chemical formula of azurite?

Answer 40

Cu₃(CO₃)₂(OH)₂

Question 41

A paired vacancy and interstitial, where an atom has moved from its original position to an interstitial site.

Answer 41

Frenkel

Question 42

After normalization a rock’s QAPF composition is Q = 10%, A = 30%, P = 60%. This rock would fall in the field of:

Answer 42

Quartz Monzonite

Question 43

Orthoclase, Microcline, and which other mineral are polymorphs of each other? A. Andalusite B. Brookite C. Sanidine D. Anatase

Answer 43

Sanidine

Question 44

Which mineral has the chemical formula of FeTiO3?

Answer 44

Ilmenite

Question 45

Which of the following minerals possess high birefringence, characterized by second-order blue to green, sometimes up to third-order yellow? A. Biotite B. Chlorite C. Olivine D. Nepheline

Answer 45

Olivine

Question 46

This is inserted to introduce a known amount of retardation in the interference color.

Answer 46

Compensator

Question 47

In petrified wood, pseudomorphism takes place by: A. Deposition B. Alteration C. Solution D. Substitution

Answer 47

Substitution

Question 48

The phenomenon where white light is separated into its constituent colors when it passes through a prism or other refractive medium.

Answer 48

Dispersion

Question 49

A rock sample contains 15% quartz, 20% alkali feldspar, 50% plagioclase, 5% biotite, and 10% hornblende. To plot this on the QAPF diagram, you would first: A. Convert all percentages to decimal value B. Normalize the QAPF percentage to 100% C. Ignore the mafic mineral D. Calculate the average percentage of all minerals

Answer 49

Normalize the QAPF percentage to 100%

Question 50

Chlorite is an index mineral for _____ metamorphism. A. Low-grade B. Medium-grade C. High-grade D. Very high-grade

Answer 50

Low grade