Diagnostic Test Questions 1-50 Flashcards
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?
0.3889
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.
Relief
The following minerals are generally idiochromatic, except: a. cinnabar b. azurite c. orthoclase d. almandine
Orthoclase
The metamorphic facies characterized by the assemblage heulandite + analcite + quartz ± clay minerals in meta-igneous rocks and greywackes.
Zeolite
Troctolite is a relative of gabbro that is ________.
Olivine-rich
Which of the following minerals is NOT pleochroic? a. tourmaline b. spodumene c. zoisite d. Feldspar
Feldspar
A volcanic rock with 53% wt SiO2 and 4 wt% (Na2O + K2O) would be classified as what on the TAS Diagram?
Basaltic Andesite
Undulatory extinction is common in which minerals? A. garnet B. olivine C. Hornblende D. Quartz
Quartz
Dessert rose is a common name for which mineral, known for its rosette-like crystal formation?
Gypsum
The boundary line between (liquid) and (liquid+solid) regions of phase diagram is known as:
Liquidus
These are dark bands that form a cross or curve pattern within the interference figure.
Isogyres
Adularia is a low-temperature variety of:
Orthoclase
A rock containing 45% olivine, 50% orthopyroxene, and 5% clinopyroxene would be classified as:
Harzburgite
A mineral with a grape-like or globular form is said to have a _____ habit.
Botryoidal
An intrusive igneous rock composed predominantly of calcium-rich plagioclase feldspar.
Anorthosite
An iridescent schiller in Labradorite is due to the presence of a ______, causing exsolution of orthoclase from the plagioclase host during cooling.
Miscibility Gap
The plagioclase feldspar series represents a ____ solid solution.
Continuous
Which of the following can be a protolith of amphibolite? A. Peridotite B. Gabbro C. Sandstone D. Slate
Gabbro
What is the size range of sand particles in mm?
1/16 to 2 mm
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
Nepheline-bearing syenite
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)
11
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
Kyanite
Bird’s eye extinction is commonly observed in: a. Pyroxene b. Biotite c. quartz d. olivine
Pyroxene
A crystal form consisting of two parallel and opposite faces. A. Pedion B. Pinacoid C. Dome D. Aphenoid
Pinacoid
Which is NOT a variety of beryl? A. Heliodor B. Emerald C. Alexandrenite D. Morganite
Alexandrite
The following minerals are radioactive except: A. Autonite B. Carnotite C. Thorianite D. None of the above
None of the above
A _____ is the smallest building block of a crystal and is a representative unit of the repetitive ____ in the crystal structure.
Unit Cell; Lattice
Which of the following is NOT a type of allochem used in Folk Classification? A. Intraclast B. Ooids C. Peloids D. Sparite
Sparite
A copper antimony sulfosalt.
Tetrahedrite
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
B
The blue variety of beryl is: A. Sapphire B. Emerald C. Morganite D. Aquamarine
Aquamarine
A chiastolite mineral with a cross-shaped inclusion pattern. A. Staurolite B. Kyanite C. Sillimanite D. Andalusite
Andalusite
In plagioclase feldspars, most common twin law is: A. Carlsbad twin law B. Albite twin law C. Pericline twin law D. Baveno twin law
Albite Twin Law
How many distinct Bravais lattices are there?
14
Which of the following mineral is NOT birefringent? A. quartz B. Calcite C. Olivine D. Spinel
Spinel
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.
Brazil Law
A sandstone with a high proportion of feldspar is classified as:
Arkose
A ternary diagram used to distinguish the calc-alkaline magma series from the tholeiitic magma series.
AFM
This is a rock that is transitional between metamorphic and igneous rock, formed when partial melting occurs during high-grade metamorphism.
Migmatite
What is the chemical formula of azurite?
Cu₃(CO₃)₂(OH)₂
A paired vacancy and interstitial, where an atom has moved from its original position to an interstitial site.
Frenkel
After normalization a rock’s QAPF composition is Q = 10%, A = 30%, P = 60%. This rock would fall in the field of:
Quartz Monzonite
Orthoclase, Microcline, and which other mineral are polymorphs of each other? A. Andalusite B. Brookite C. Sanidine D. Anatase
Sanidine
Which mineral has the chemical formula of FeTiO3?
Ilmenite
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
Olivine
This is inserted to introduce a known amount of retardation in the interference color.
Compensator
In petrified wood, pseudomorphism takes place by: A. Deposition B. Alteration C. Solution D. Substitution
Substitution
The phenomenon where white light is separated into its constituent colors when it passes through a prism or other refractive medium.
Dispersion
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
Normalize the QAPF percentage to 100%
Chlorite is an index mineral for _____ metamorphism. A. Low-grade B. Medium-grade C. High-grade D. Very high-grade
Low grade
