ESS 101B: Earth and Space Sciences — Laboratory Lab 6: Metamorphic Rocks
ESS 101 B LABORATORY 6 COMPLETE ASSIGNMENT: METAMORPHIC ROCKS —
IDENTIFICATION, CLASSIFICATION & ANALYSIS COMPLETE SOLUTION 2026
ESS 101B: Earth and Space Sciences
Laboratory 6: Metamorphic Rocks
University of Washington | Department of Earth & Space Sciences
Name: Section / TA: __________________________
_________________________________
Student ID: Date:
_________________________________ ______________________________________
Lab Objectives
By the end of this laboratory, you will be able to:
• Identify and describe common metamorphic rocks using their physical properties.
• Distinguish between foliated and non-foliated metamorphic textures.
• Interpret metamorphic grade and infer protolith (parent rock) from rock characteristics.
• Understand the relationship between pressure, temperature, and metamorphic rock type.
• Recognize index minerals and their association with metamorphic zones.
Background & Introduction
Metamorphic rocks form when pre-existing rocks — called protoliths — are subjected to high
temperatures, high pressures, chemically active fluids, or some combination of these conditions. This
transformation occurs without melting the rock. The heat and pressure cause mineral recrystallization,
new mineral growth, and changes in texture.
Key Concepts
• Foliated textures (slate, phyllite, schist, gneiss) result from preferential alignment of platy minerals
under directed pressure.
• Non-foliated textures (marble, quartzite, hornfels) lack mineral alignment, often forming from
monomineralic protoliths or contact metamorphism.
• Metamorphic grade reflects the intensity of metamorphism — low grade (low T/P) to high grade
(high T/P).
University of Washington | Department of Earth & Space Sciences Page 1
, ESS 101B: Earth and Space Sciences — Laboratory Lab 6: Metamorphic Rocks
• Index minerals — chlorite, biotite, garnet, staurolite, kyanite, sillimanite — mark specific pressure-
temperature conditions.
Reference: Common Metamorphic Rocks
Rock Name Grade Texture Foliated? Protolith Key Characteristics
Slate Low Fine- Yes Shale/mudstone Dull luster, breaks into flat
grained sheets, pencil-like cleavage
Phyllite Low- Fine- Yes Shale/mudstone Silky sheen on foliation planes,
Med grained slight waviness
Schist Medium Medium- Yes Shale/mudstone Visible platy minerals (mica),
coarse sparkly surface
Gneiss High Coarse Yes Granite/schist Alternating light/dark bands
(gneissic banding)
Marble Variable Coarse- No Limestone Calcite/dolomite crystals,
medium effervesces in HCl
Quartzite Variable Coarse- No Sandstone/chert Very hard, glassy luster, quartz
medium grains fused together
Hornfels High Fine- No Any fine-grained Very hard, dense, dark,
(contact) grained conchoidal fracture
Amphibolite Medium- Coarse Weakly Basalt/gabbro Hornblende + plagioclase, dark
High green-black
Eclogite Very Coarse Weakly Basalt/gabbro Garnet + omphacite, red +
High green, high-P indicator
Part A: Rock Identification (30 points)
Using the rock specimens provided at your lab station, complete the identification table below. Examine
each rock carefully and record your observations. Use the reference table above and your textbook to
help determine rock names. Write legibly.
Instructions: For each rock sample (numbered 1–8), record the following:
• Color — describe the dominant color(s)
• Texture — describe what you observe (e.g., fine-grained, coarse-grained, banded, glassy)
• Grain Size — fine (<1 mm), medium (1–5 mm), or coarse (>5 mm)
• Foliated — Yes or No
• Protolith — what rock was it before metamorphism?
• Metamorphic Grade — Low, Medium, High, or Contact
• Rock Name — use the reference table and your observations
• Key Minerals — list 1–3 minerals you can identify
Rock Color Texture Grain Foliated? Protolith Metamorphic Rock Key Minerals
# Size Grade Name
University of Washington | Department of Earth & Space Sciences Page 2
ESS 101 B LABORATORY 6 COMPLETE ASSIGNMENT: METAMORPHIC ROCKS —
IDENTIFICATION, CLASSIFICATION & ANALYSIS COMPLETE SOLUTION 2026
ESS 101B: Earth and Space Sciences
Laboratory 6: Metamorphic Rocks
University of Washington | Department of Earth & Space Sciences
Name: Section / TA: __________________________
_________________________________
Student ID: Date:
_________________________________ ______________________________________
Lab Objectives
By the end of this laboratory, you will be able to:
• Identify and describe common metamorphic rocks using their physical properties.
• Distinguish between foliated and non-foliated metamorphic textures.
• Interpret metamorphic grade and infer protolith (parent rock) from rock characteristics.
• Understand the relationship between pressure, temperature, and metamorphic rock type.
• Recognize index minerals and their association with metamorphic zones.
Background & Introduction
Metamorphic rocks form when pre-existing rocks — called protoliths — are subjected to high
temperatures, high pressures, chemically active fluids, or some combination of these conditions. This
transformation occurs without melting the rock. The heat and pressure cause mineral recrystallization,
new mineral growth, and changes in texture.
Key Concepts
• Foliated textures (slate, phyllite, schist, gneiss) result from preferential alignment of platy minerals
under directed pressure.
• Non-foliated textures (marble, quartzite, hornfels) lack mineral alignment, often forming from
monomineralic protoliths or contact metamorphism.
• Metamorphic grade reflects the intensity of metamorphism — low grade (low T/P) to high grade
(high T/P).
University of Washington | Department of Earth & Space Sciences Page 1
, ESS 101B: Earth and Space Sciences — Laboratory Lab 6: Metamorphic Rocks
• Index minerals — chlorite, biotite, garnet, staurolite, kyanite, sillimanite — mark specific pressure-
temperature conditions.
Reference: Common Metamorphic Rocks
Rock Name Grade Texture Foliated? Protolith Key Characteristics
Slate Low Fine- Yes Shale/mudstone Dull luster, breaks into flat
grained sheets, pencil-like cleavage
Phyllite Low- Fine- Yes Shale/mudstone Silky sheen on foliation planes,
Med grained slight waviness
Schist Medium Medium- Yes Shale/mudstone Visible platy minerals (mica),
coarse sparkly surface
Gneiss High Coarse Yes Granite/schist Alternating light/dark bands
(gneissic banding)
Marble Variable Coarse- No Limestone Calcite/dolomite crystals,
medium effervesces in HCl
Quartzite Variable Coarse- No Sandstone/chert Very hard, glassy luster, quartz
medium grains fused together
Hornfels High Fine- No Any fine-grained Very hard, dense, dark,
(contact) grained conchoidal fracture
Amphibolite Medium- Coarse Weakly Basalt/gabbro Hornblende + plagioclase, dark
High green-black
Eclogite Very Coarse Weakly Basalt/gabbro Garnet + omphacite, red +
High green, high-P indicator
Part A: Rock Identification (30 points)
Using the rock specimens provided at your lab station, complete the identification table below. Examine
each rock carefully and record your observations. Use the reference table above and your textbook to
help determine rock names. Write legibly.
Instructions: For each rock sample (numbered 1–8), record the following:
• Color — describe the dominant color(s)
• Texture — describe what you observe (e.g., fine-grained, coarse-grained, banded, glassy)
• Grain Size — fine (<1 mm), medium (1–5 mm), or coarse (>5 mm)
• Foliated — Yes or No
• Protolith — what rock was it before metamorphism?
• Metamorphic Grade — Low, Medium, High, or Contact
• Rock Name — use the reference table and your observations
• Key Minerals — list 1–3 minerals you can identify
Rock Color Texture Grain Foliated? Protolith Metamorphic Rock Key Minerals
# Size Grade Name
University of Washington | Department of Earth & Space Sciences Page 2
