1|Page
GL101 EXAM LATEST 2026 ACTUAL EXAM WITH COMPLETE
QUESTIONS AND CORRECT DETAILED ANSWERS (100% VERIFIED
ANSWERS) |ALREADY GRADED A+| ||PROFESSOR VERIFIED||
||BRANDNEW!!!||
The most abundant elements in common crustal igneous rocks
are ________.
A) calcium and sodium
B) iron and magnesium
C) oxygen and silicon
D) granite and basalt - ANSWER-C
As the silica content varies from less than 40% to more than 70%
there is a systematic ________.
A) decrease in calcium, magnesium, and iron with an increase in
sodium and potassium
B) increase in calcium, magnesium, and iron with a decrease in
sodium and potassium
C) increase in the temperature at which point melting begins
D) decrease in the quartz content of the rocks - ANSWER-A
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Which igneous texture indicates two, distinctly different sizes of
mineral grains?
A) aphanitic
B) porphyritic
C) phaneritic
D) glassy - ANSWER-B
When a rock has a two-stage cooling history (slow then fast) or
has minerals that crystallized at different temperatures and grew
at different rates it is ________.
A) aphanitic
B) phaneritic
C) porphyritic
D) pyroclastic - ANSWER-C
What do pumice and obsidian have in common?
A) basaltic composition
B) glassy texture
C) ultramafic composition
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D) phaneritic texture - ANSWER-B
________ typically exhibit pyroclastic textures.
A) Granites
B) Gabbros
C) Diorites
D) Welded tuffs - ANSWER-D
What is the rock colour (total % of dark minerals) of a typical
granite or rhyolite?
A) < 25%
B) 25-45%
C) 45-85%
D) > 85% - ANSWER-A
Which of the following igneous rocks usually exhibit aphanitic
texture?
A) granite, gabbro
B) andesite, rhyolite
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C) andesite, diorite
D) rhyolite, gabbro - ANSWER-B
Which texture would be most unlikely to occur in an extrusive
igneous rock?
A) pyroclastic
B) glassy
C) aphanitic
D) phaneritic - ANSWER-D
What name would you assign to a dense phaneritic green rock
having olivine and pyroxene as dominant minerals?
A) peridotite
B) granite
C) diorite
D) gabbro - ANSWER-A
What would you name a light pink, aphanitic, fragmental
pyroclastic with sparse quartz phenocrysts?
GL101 EXAM LATEST 2026 ACTUAL EXAM WITH COMPLETE
QUESTIONS AND CORRECT DETAILED ANSWERS (100% VERIFIED
ANSWERS) |ALREADY GRADED A+| ||PROFESSOR VERIFIED||
||BRANDNEW!!!||
The most abundant elements in common crustal igneous rocks
are ________.
A) calcium and sodium
B) iron and magnesium
C) oxygen and silicon
D) granite and basalt - ANSWER-C
As the silica content varies from less than 40% to more than 70%
there is a systematic ________.
A) decrease in calcium, magnesium, and iron with an increase in
sodium and potassium
B) increase in calcium, magnesium, and iron with a decrease in
sodium and potassium
C) increase in the temperature at which point melting begins
D) decrease in the quartz content of the rocks - ANSWER-A
,2|Page
Which igneous texture indicates two, distinctly different sizes of
mineral grains?
A) aphanitic
B) porphyritic
C) phaneritic
D) glassy - ANSWER-B
When a rock has a two-stage cooling history (slow then fast) or
has minerals that crystallized at different temperatures and grew
at different rates it is ________.
A) aphanitic
B) phaneritic
C) porphyritic
D) pyroclastic - ANSWER-C
What do pumice and obsidian have in common?
A) basaltic composition
B) glassy texture
C) ultramafic composition
,3|Page
D) phaneritic texture - ANSWER-B
________ typically exhibit pyroclastic textures.
A) Granites
B) Gabbros
C) Diorites
D) Welded tuffs - ANSWER-D
What is the rock colour (total % of dark minerals) of a typical
granite or rhyolite?
A) < 25%
B) 25-45%
C) 45-85%
D) > 85% - ANSWER-A
Which of the following igneous rocks usually exhibit aphanitic
texture?
A) granite, gabbro
B) andesite, rhyolite
, 4|Page
C) andesite, diorite
D) rhyolite, gabbro - ANSWER-B
Which texture would be most unlikely to occur in an extrusive
igneous rock?
A) pyroclastic
B) glassy
C) aphanitic
D) phaneritic - ANSWER-D
What name would you assign to a dense phaneritic green rock
having olivine and pyroxene as dominant minerals?
A) peridotite
B) granite
C) diorite
D) gabbro - ANSWER-A
What would you name a light pink, aphanitic, fragmental
pyroclastic with sparse quartz phenocrysts?
