GLG 103 Lab 4: Minerals | Questions and
Answers | 2026/2027 Updated | 100% Correct
- Arizona State University.
Practice Question Bank & Answer Rationale
THIS PACK CONTAINS
50 exam-style multiple-choice questions. Each question includes the correct answer and a complete rationale
for focused revision.
COVERAGE
This laboratory exam assesses mastery of mineral identification and classification as taught in GLG 103 Lab
4. Students must apply physical-property tests (hardness, cleavage, fracture, luster, streak, specific gravity,
magnetism, effervescence), crystal-system and silicate-structure reasoning, and Bowen's Reaction Series to
identify hand specimens and interpret mineral formation environments.
STUDY GUIDE
Recommended duration: 2 hours. Passing target: 70%.
HIGHP - Page 1 of 17
,1. A mineral specimen exhibits two distinct cleavage directions intersecting at
approximately 90°, and its hardness is 6. Which mineral is most likely, and what is the
structural basis for its cleavage?
[ ] A. Amphibole; double-chain silicate with cleavage at 56°/124°
[ ] B. Plagioclase feldspar; framework silicate with two orthogonal cleavages
[ ] C. Pyroxene; single-chain silicate with two cleavages near 90°
[ ] D. Mica; sheet silicate with one perfect basal cleavage
CORRECT: C. Pyroxene; single-chain silicate with two cleavages near 90°
Pyroxene is a single-chain silicate whose chains align such that two cleavages meet at nearly 90°, and its
hardness (~5-6) matches. Amphibole has 56°/124° cleavage, plagioclase has two cleavages but is a
framework silicate with hardness 6 and often striations, and mica has only one perfect cleavage.
2. Which property is most diagnostic for distinguishing calcite from dolomite in a
laboratory setting?
[ ] A. Calcite effervesces vigorously in cold dilute HCl; dolomite effervesces only when powdered or in
warm acid
[ ] B. Calcite has a higher hardness than dolomite
[ ] C. Dolomite has perfect rhombohedral cleavage, calcite does not
[ ] D. Calcite is magnetic, dolomite is not
CORRECT: A. Calcite effervesces vigorously in cold dilute HCl; dolomite effervesces only when
powdered or in warm acid
Calcite reacts vigorously with cold dilute HCl, while dolomite reacts weakly or only when powdered/warmed
due to its Ca-Mg carbonate composition. Both have rhombohedral cleavage and similar hardness (3-4), and
neither is magnetic.
3. A mineral has a metallic luster, leaves a reddish-brown streak, and has a hardness of
5-6. It is attracted to a magnet. Which mineral is it?
[ ] A. Hematite
[ ] B. Magnetite
[ ] C. Pyrite
[ ] D. Galena
CORRECT: B. Magnetite
Magnetite is strongly magnetic, metallic, has a black streak (not reddish-brown), and hardness 5.5-6.5.
Hematite can be magnetic in some varieties but typically has a reddish-brown streak and is not strongly
attracted to a magnet. Pyrite is non-magnetic with a greenish-black streak, and galena is non-magnetic with a
gray streak.
HIGHP - Page 2 of 17
, 4. Which silicate structure is characterized by a three-dimensional framework of
tetrahedra where all four oxygens are shared, resulting in no distinct cleavage?
[ ] A. Isolated tetrahedra
[ ] B. Single chain
[ ] C. Double chain
[ ] D. Framework
CORRECT: D. Framework
Framework silicates (e.g., quartz, feldspars) share all four oxygens, creating a 3D network with no preferred
cleavage planes. Isolated tetrahedra (olivine) share no oxygens, single chains (pyroxene) share two, and
double chains (amphibole) share two or three, all producing distinct cleavage.
5. According to Bowen's Reaction Series, which mineral crystallizes at the highest
temperature from a mafic magma?
[ ] A. Quartz
[ ] B. Muscovite
[ ] C. Olivine
[ ] D. Biotite
CORRECT: C. Olivine
Olivine is the first mineral to crystallize in Bowen's discontinuous series at the highest temperature
(~1200-1300°C). Quartz and muscovite crystallize at much lower temperatures, and biotite crystallizes at
intermediate temperatures.
6. A mineral specimen has a hardness of 3, perfect rhombohedral cleavage, and
effervesces in dilute HCl. Which mineral is it?
[ ] A. Halite
[ ] B. Calcite
[ ] C. Fluorite
[ ] D. Gypsum
CORRECT: B. Calcite
Calcite has hardness 3, perfect rhombohedral cleavage, and reacts vigorously with dilute HCl. Halite has
cubic cleavage and a salty taste, fluorite has octahedral cleavage and no effervescence, and gypsum has
hardness 2 and no effervescence.
7. Which mineral is an example of a sheet silicate with perfect basal cleavage and a pearly
luster?
[ ] A. Quartz
[ ] B. Muscovite
HIGHP - Page 3 of 17
Answers | 2026/2027 Updated | 100% Correct
- Arizona State University.
Practice Question Bank & Answer Rationale
THIS PACK CONTAINS
50 exam-style multiple-choice questions. Each question includes the correct answer and a complete rationale
for focused revision.
COVERAGE
This laboratory exam assesses mastery of mineral identification and classification as taught in GLG 103 Lab
4. Students must apply physical-property tests (hardness, cleavage, fracture, luster, streak, specific gravity,
magnetism, effervescence), crystal-system and silicate-structure reasoning, and Bowen's Reaction Series to
identify hand specimens and interpret mineral formation environments.
STUDY GUIDE
Recommended duration: 2 hours. Passing target: 70%.
HIGHP - Page 1 of 17
,1. A mineral specimen exhibits two distinct cleavage directions intersecting at
approximately 90°, and its hardness is 6. Which mineral is most likely, and what is the
structural basis for its cleavage?
[ ] A. Amphibole; double-chain silicate with cleavage at 56°/124°
[ ] B. Plagioclase feldspar; framework silicate with two orthogonal cleavages
[ ] C. Pyroxene; single-chain silicate with two cleavages near 90°
[ ] D. Mica; sheet silicate with one perfect basal cleavage
CORRECT: C. Pyroxene; single-chain silicate with two cleavages near 90°
Pyroxene is a single-chain silicate whose chains align such that two cleavages meet at nearly 90°, and its
hardness (~5-6) matches. Amphibole has 56°/124° cleavage, plagioclase has two cleavages but is a
framework silicate with hardness 6 and often striations, and mica has only one perfect cleavage.
2. Which property is most diagnostic for distinguishing calcite from dolomite in a
laboratory setting?
[ ] A. Calcite effervesces vigorously in cold dilute HCl; dolomite effervesces only when powdered or in
warm acid
[ ] B. Calcite has a higher hardness than dolomite
[ ] C. Dolomite has perfect rhombohedral cleavage, calcite does not
[ ] D. Calcite is magnetic, dolomite is not
CORRECT: A. Calcite effervesces vigorously in cold dilute HCl; dolomite effervesces only when
powdered or in warm acid
Calcite reacts vigorously with cold dilute HCl, while dolomite reacts weakly or only when powdered/warmed
due to its Ca-Mg carbonate composition. Both have rhombohedral cleavage and similar hardness (3-4), and
neither is magnetic.
3. A mineral has a metallic luster, leaves a reddish-brown streak, and has a hardness of
5-6. It is attracted to a magnet. Which mineral is it?
[ ] A. Hematite
[ ] B. Magnetite
[ ] C. Pyrite
[ ] D. Galena
CORRECT: B. Magnetite
Magnetite is strongly magnetic, metallic, has a black streak (not reddish-brown), and hardness 5.5-6.5.
Hematite can be magnetic in some varieties but typically has a reddish-brown streak and is not strongly
attracted to a magnet. Pyrite is non-magnetic with a greenish-black streak, and galena is non-magnetic with a
gray streak.
HIGHP - Page 2 of 17
, 4. Which silicate structure is characterized by a three-dimensional framework of
tetrahedra where all four oxygens are shared, resulting in no distinct cleavage?
[ ] A. Isolated tetrahedra
[ ] B. Single chain
[ ] C. Double chain
[ ] D. Framework
CORRECT: D. Framework
Framework silicates (e.g., quartz, feldspars) share all four oxygens, creating a 3D network with no preferred
cleavage planes. Isolated tetrahedra (olivine) share no oxygens, single chains (pyroxene) share two, and
double chains (amphibole) share two or three, all producing distinct cleavage.
5. According to Bowen's Reaction Series, which mineral crystallizes at the highest
temperature from a mafic magma?
[ ] A. Quartz
[ ] B. Muscovite
[ ] C. Olivine
[ ] D. Biotite
CORRECT: C. Olivine
Olivine is the first mineral to crystallize in Bowen's discontinuous series at the highest temperature
(~1200-1300°C). Quartz and muscovite crystallize at much lower temperatures, and biotite crystallizes at
intermediate temperatures.
6. A mineral specimen has a hardness of 3, perfect rhombohedral cleavage, and
effervesces in dilute HCl. Which mineral is it?
[ ] A. Halite
[ ] B. Calcite
[ ] C. Fluorite
[ ] D. Gypsum
CORRECT: B. Calcite
Calcite has hardness 3, perfect rhombohedral cleavage, and reacts vigorously with dilute HCl. Halite has
cubic cleavage and a salty taste, fluorite has octahedral cleavage and no effervescence, and gypsum has
hardness 2 and no effervescence.
7. Which mineral is an example of a sheet silicate with perfect basal cleavage and a pearly
luster?
[ ] A. Quartz
[ ] B. Muscovite
HIGHP - Page 3 of 17
