Best examples of rock sample analysis lab report examples for geology students

Rock sample analysis lab reports are where field observations, lab data, and geologic reasoning all meet. Instructors use them to check whether you can:

• Describe rocks accurately and consistently
• Use proper terminology for textures and minerals
• Connect individual samples to larger geologic processes
• Communicate data and uncertainty clearly

The best examples of rock sample analysis lab report examples don’t just list minerals; they tell a geologic story that’s backed by observations and measurements.

Igneous rock sample: basalt from a mid-ocean ridge

This is one of the most common example of rock sample analysis lab report sections you’ll see in intro petrology.

Sample context
Hand specimen and thin section of a fine-grained, dark-colored igneous rock collected from a mid-ocean ridge setting (hypothetical cruise data modeled after modern surveys by programs such as the U.S. Geological Survey).

Methods (summarized)
In a strong student report, the methods are short but specific:

• Hand sample description under binocular microscope
• Thin-section petrography using plane-polarized and cross-polarized light
• Whole-rock major element chemistry via XRF (values provided by instructor)

Results (condensed example)
The best examples include quantitative ranges rather than vague phrases:

• Color index: ~80–90% mafic minerals
• Texture: aphanitic to porphyritic, intergranular groundmass
• Phenocrysts: plagioclase laths (1–3 mm), subhedral to euhedral
• Groundmass: clinopyroxene + plagioclase, minor Fe-Ti oxides
• XRF: ~49 wt% SiO₂, 10 wt% FeOᵗ, 10 wt% CaO, Mg# ~60

Interpretation snippet (modeled text)

The fine-grained, aphanitic texture and high mafic mineral content indicate rapid cooling of a mafic magma at or near the surface. The whole-rock chemistry and Mg# are consistent with a tholeiitic basalt typical of mid-ocean ridge basalts (MORB). The presence of plagioclase phenocrysts in a finer-grained groundmass suggests a two-stage cooling history: slower cooling at depth followed by rapid quenching during extrusion on the seafloor.

This kind of paragraph is exactly what appears in the best examples of rock sample analysis lab report examples: clear link between observations and tectonic setting, with no dramatic overstatements.

Sedimentary rock sample: quartz sandstone from a beach environment

Another classic example of rock sample analysis lab report content focuses on sedimentary textures and provenance.

Sample context
Well-sorted, light-colored sandstone from a modern beach or ancient shoreline deposit.

Key observations you’d expect in good examples include:

• Grain size: medium sand (0.25–0.5 mm)
• Sorting: well sorted
• Rounding: subrounded to rounded
• Composition: >90% quartz, minor feldspar and lithic fragments
• Sedimentary structures: planar bedding, low-angle cross-beds, ripple marks

Interpretation snippet (modeled text)

The dominance of well-rounded, well-sorted quartz grains indicates prolonged transport and mechanical abrasion, consistent with a high-energy shoreline environment. The scarcity of feldspar and lithic fragments suggests intense chemical weathering and multiple cycles of reworking, typical of mature passive-margin beach systems. Cross-bedding and ripple marks point to oscillatory flow in a shallow marine setting.

In many real examples of rock sample analysis lab report examples, instructors want you to connect this kind of sandstone to plate-margin type (passive vs active) and long-term climate (warm, humid weathering vs cold, arid conditions), ideally with a short reference to modern analogs.

Metamorphic rock sample: schist from a regional metamorphic belt

Metamorphic samples are where many students start to struggle, so the best examples really stand out.

Sample context
Medium- to coarse-grained mica schist from a regional metamorphic terrane.

Observations commonly seen in strong reports:

• Texture: foliated, schistose
• Major minerals: muscovite, biotite, quartz, garnet porphyroblasts
• Foliation: defined by aligned micas wrapping around garnet
• Accessory minerals: staurolite, opaque oxides

Interpretation snippet (modeled text)

The presence of garnet and staurolite, together with muscovite and biotite, suggests amphibolite-facies metamorphism of a pelitic protolith. The strong schistosity and mineral alignment indicate deformation under directed pressure, likely associated with continental collision. Garnet porphyroblasts that overgrow the foliation in places record changing pressure–temperature conditions during progressive metamorphism.

This kind of paragraph is a textbook example of rock sample analysis lab report writing: specific mineral indicators tied to P–T conditions and tectonic setting.

Thin-section–focused example: granite with zoned plagioclase

Some courses emphasize optical mineralogy, so good examples include detailed thin-section descriptions.

Sample context
Coarse-grained granite collected from a continental batholith.

What high-quality examples include:

• Modal mineralogy estimate: ~30% quartz, 40% K-feldspar, 25% plagioclase, 5% biotite + accessories
• Textures: hypidiomorphic granular; plagioclase shows normal zoning; quartz exhibits undulose extinction
• Alteration: partial sericitization of plagioclase, chloritization of biotite

Interpretation snippet (modeled text)

The modal mineralogy and presence of both K-feldspar and plagioclase classify the sample as a granite. Normal zoning in plagioclase records fractional crystallization from a more calcic to a more sodic composition as the magma cooled. Undulose extinction in quartz and bent biotite cleavage suggest low- to moderate-intensity solid-state deformation after crystallization, possibly related to regional tectonic shortening.

In the best examples of rock sample analysis lab report examples from upper-level petrology courses, students support these interpretations with phase diagrams or published data from similar batholiths, often citing sources from university departments such as MIT’s OpenCourseWare geology materials.

Geochemistry-heavy example: basalt REE patterns

By 2024–2025, many geology programs incorporate more geochemical data, even in undergraduate labs. That means modern examples include simple trace-element plots.

Sample context
Two basalt samples: one from a mid-ocean ridge, one from an ocean island setting.

Key data features you might see summarized:

• MORB sample: flat to slightly depleted light rare earth elements (LREE), low incompatible element concentrations
• Ocean island basalt (OIB): LREE-enriched pattern, higher incompatible elements

Interpretation snippet (modeled text)

Chondrite-normalized REE patterns show a relatively flat profile for the MORB sample, consistent with partial melting of a depleted upper mantle source. In contrast, the OIB sample exhibits LREE enrichment, suggesting derivation from an enriched mantle plume or metasomatized mantle source. These geochemical differences support the tectonic interpretations based on field relationships and petrography.

When you look at real examples of rock sample analysis lab report examples from advanced classes, this geochemical reasoning is often backed by a short comparison to published MORB and OIB patterns from international datasets, such as those compiled by the USGS or university research groups.

Environmental and engineering example: weathered granite for slope stability

Not every example of rock sample analysis lab report is purely academic. Environmental and engineering geology labs increasingly use applied case studies.

Sample context
Highly weathered granite from a proposed construction site on a hillside.

What strong applied examples include:

• Degree of weathering: corestone–saprolite profile; clay-rich matrix
• Discontinuities: fractures, joints, foliation planes
• Strength estimates: point-load tests or Schmidt hammer values provided
• Mineralogy: kaolinite and secondary clays replacing feldspar

Interpretation snippet (modeled text)

Extensive chemical weathering of feldspar to clay has significantly reduced rock mass strength, transforming much of the original granite into saprolite. Closely spaced joints and fractures provide potential failure planes, particularly where they daylight on the slope face. Laboratory strength data, combined with field observations, indicate that cut slopes in this material will require engineered reinforcement and drainage to reduce landslide risk.

Reports like this mirror real-world practice in geotechnical and environmental work, and many instructors encourage students to reference guidelines from agencies such as the U.S. Geological Survey or state geological surveys for context.

How to structure your own report using these examples

Once you’ve read several of the best examples of rock sample analysis lab report examples, patterns emerge. Strong reports typically follow a consistent structure:

Title and sample ID
Clear, specific titles: “Petrographic and Geochemical Analysis of Basalt Sample B-14 from the Juan de Fuca Ridge.” Avoid vague labels like “Rock Lab Report.”

Introduction
A few short paragraphs that:

• Identify the rock type and location
• State the main questions (e.g., tectonic setting, metamorphic grade, depositional environment)
• Briefly mention what methods will be used

Methods
Concise, past-tense descriptions:

• How you prepared and observed the sample
• What instruments or reference charts you used
• Any standards or calibration steps, if provided in the lab

Results
This is where many weaker reports fall apart. In high-quality examples of rock sample analysis lab report examples, the results section:

• Separates observations from interpretations
• Uses consistent terminology (e.g., grain size classes, mineral names, textural terms)
• Includes quantitative data where available (percentages, grain size ranges, geochemical values)

Interpretation and discussion
This section connects your sample to the broader geologic story. Strong examples include:

• Clear classification (e.g., basalt vs andesite, schist vs gneiss)
• Tectonic or environmental setting (ridge, subduction zone, passive margin, orogenic belt)
• Pressure–temperature estimates for metamorphic rocks when appropriate
• Comparison to published data or regional geology

Uncertainty and limitations
Real examples of rock sample analysis lab report examples don’t pretend the data are perfect. They mention:

• Thin-section quality issues
• Limited sample size
• Ambiguous textures or alteration
• Assumptions made in classification

A short paragraph acknowledging these limitations shows you understand how real science works.

Trends in geology lab reports for 2024–2025

Geology education has shifted noticeably in the last few years, and that shows up in current examples of rock sample analysis lab report examples.

More digital tools
Many labs now use digital microscopes, online thin-section libraries, and open-source plotting tools. Some courses incorporate virtual thin sections or 3D rock models, especially in hybrid or online formats.

Stronger emphasis on data literacy
Students are expected to:

• Plot simple geochemical diagrams
• Use spreadsheets for data tables and graphs
• Interpret basic statistical summaries of measurements

Integration with environmental and hazard topics
Instructors increasingly tie rock sample analysis to:

• Landslide risk assessment
• Groundwater contamination pathways
• Earthquake hazard and fault-zone rocks

You’ll see these themes in many of the best examples of rock sample analysis lab report examples from 2024–2025, especially in upper-division courses.

For additional context on how earth science education is evolving, it’s worth browsing materials from organizations such as the American Geosciences Institute, which regularly discusses curriculum trends and teaching resources.

FAQ: examples of rock sample analysis lab report examples

Q: Where can I find more real examples of rock sample analysis lab report examples online?
Many geology departments post sample lab reports or lab manuals. Search for phrases like “petrology lab report example pdf” along with .edu. Some universities host open course materials through platforms similar to MIT OpenCourseWare, which often include example of graded reports, rubrics, and sample write-ups.

Q: What’s the most common mistake students make in an example of a rock sample analysis lab report?
The most common issue is mixing interpretation into the results section. Instructors want raw observations first, then interpretation. Another frequent problem in weaker examples includes vague descriptions like “dark minerals” instead of naming pyroxene, amphibole, or biotite when possible.

Q: How detailed should mineral descriptions be in a typical rock sample analysis lab report?
For intro courses, you’re usually expected to identify major minerals, estimate rough percentages, and describe textures. Advanced courses expect more: optical properties in thin section, zoning, alteration, and relationships between minerals. Looking at high-level examples of rock sample analysis lab report examples from upper-division classes can help you see how much detail is appropriate.

Q: Can I reuse wording from published examples of rock sample analysis lab report examples?
You can absolutely study the structure, organization, and style of good reports, but you should write your own descriptions and interpretations. Copying text is plagiarism. Instead, use published examples as a checklist: do you have a clear introduction, methods, results, and interpretation? Are your mineral and texture terms used correctly?

Q: Are figures and tables required in every example of a rock sample analysis lab report?
They’re not always required, but they almost always improve clarity. Tables work well for mineral modes, grain size ranges, and geochemical data. Simple graphs (like REE patterns or Harker diagrams) are common in more advanced reports. Even when your instructor doesn’t require them, the strongest examples include at least one well-labeled table summarizing key data.

If you treat these examples of rock sample analysis lab report examples as models—not scripts—you’ll end up with reports that are clearer, more professional, and much easier for your instructors to grade.