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Minerals and Rocks – CBSE NCERT Study Resources

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11th

11th - Geography

Minerals and Rocks

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Overview of the Chapter: Minerals and Rocks

This chapter introduces students to the fundamental concepts of minerals and rocks, their formation, classification, and significance in Earth's geology. It covers the physical and chemical properties of minerals, types of rocks, and the rock cycle as per the CBSE Grade 11 Geography curriculum.

Mineral: A naturally occurring inorganic substance with a definite chemical composition and ordered atomic structure.

Rock: An aggregate of one or more minerals, formed through geological processes.

Types of Minerals

Minerals are classified based on their chemical composition and physical properties. The major groups include:

  • Silicate Minerals: Contain silicon and oxygen (e.g., quartz, feldspar).
  • Non-Silicate Minerals: Do not contain silicon (e.g., calcite, gypsum).

Physical Properties of Minerals

Key properties used for mineral identification:

  • Color
  • Streak
  • Luster
  • Hardness (Mohs scale)
  • Cleavage and Fracture

Types of Rocks

Rocks are categorized into three major types based on their formation:

  • Igneous Rocks: Formed from cooling and solidification of magma or lava (e.g., granite, basalt).
  • Sedimentary Rocks: Formed from accumulation and compaction of sediments (e.g., sandstone, limestone).
  • Metamorphic Rocks: Formed from transformation of existing rocks under heat and pressure (e.g., marble, slate).

The Rock Cycle

The rock cycle illustrates the continuous transformation of rocks from one type to another through geological processes such as weathering, erosion, melting, and recrystallization.

Economic Significance of Minerals and Rocks

Minerals and rocks are vital resources for industries, construction, energy production, and technology. Their sustainable extraction and conservation are crucial for environmental balance.

All Question Types with Solutions – CBSE Exam Pattern

Explore a complete set of CBSE-style questions with detailed solutions, categorized by marks and question types. Ideal for exam preparation, revision and practice.

Very Short Answer (1 Mark) – with Solutions (CBSE Pattern)

These are 1-mark questions requiring direct, concise answers. Ideal for quick recall and concept clarity.

Question 1:
Define mineral in geological terms.
Answer:

A naturally occurring inorganic solid with a definite chemical composition.

Question 2:
Name the hardest mineral on the Mohs scale.
Answer:

Diamond (Mohs hardness: 10).

Question 3:
Which rock type forms from cooled magma?
Answer:

Igneous rocks like basalt or granite.

Question 4:
List two ferrous minerals.
Answer:
  • Iron ore
  • Manganese
Question 5:
What is the primary component of limestone?
Answer:

Calcium carbonate (CaCO3).

Question 6:
Which GIS data type represents elevation?
Answer:

Digital Elevation Model (DEM).

Question 7:
Compare igneous and sedimentary rocks.
Answer:
FeatureIgneousSedimentary
FormationCooled magmaCompacted sediments
TextureCrystallineLayered
ExamplesGraniteSandstone
FossilsRareCommon
PorosityLowHigh
Question 8:
Name the mineral used in making cement.
Answer:

Gypsum (with limestone).

Question 9:
What process forms metamorphic rocks?
Answer:

Heat and pressure on existing rocks.

Question 10:
Which Indian state is richest in bauxite?
Answer:

Odisha (our textbook shows 50% reserves).

Question 11:
Define ore.
Answer:

Rock containing valuable minerals for extraction.

Question 12:
Give an example of a plutonic igneous rock.
Answer:

Granite (forms deep underground).

Question 13:
What property distinguishes quartz from calcite?
Answer:

Quartz has higher hardness (7 vs 3).

Question 14:
Define mineral in geology.
Answer:

A naturally occurring inorganic solid with a definite chemical composition.

Question 15:
Name two ferrous minerals.
Answer:
  • Iron ore
  • Manganese
Question 16:
What is the hardest mineral on Mohs scale?
Answer:

Diamond (Mohs hardness 10).

Question 17:
Classify igneous rocks based on origin.
Answer:
  • Intrusive
  • Extrusive
Question 18:
Give an example of metamorphic rock formed from limestone.
Answer:

Marble.

Question 19:
What process forms sedimentary rocks?
Answer:

Lithification of sediments.

Question 20:
Which mineral is called 'Brown Coal'?
Answer:

Lignite.

Question 21:
Name the ore of aluminium.
Answer:

Bauxite.

Question 22:
What are placer deposits?
Answer:

Minerals concentrated by water movement.

Question 23:
Identify the non-metallic mineral used in cement.
Answer:

Gypsum.

Question 24:
Which rock contains fossils?
Answer:

Sedimentary rock.

Question 25:
What is the parent rock of slate?
Answer:

Shale.

Question 26:
Name two energy minerals.
Answer:
  • Coal
  • Uranium
Question 27:
Which mineral property refers to color in powdered form?
Answer:

Streak.

Question 28:
Define minerals in geological terms.
Answer:

In geology, minerals are naturally occurring, inorganic solids with a definite chemical composition and ordered atomic structure. They are the building blocks of rocks.

Question 29:
Name the three major types of rocks based on their formation.
Answer:
  • Igneous rocks (formed from cooling magma/lava)
  • Sedimentary rocks (formed from compaction/cementation)
  • Metamorphic rocks (formed from heat/pressure)
Question 30:
What is the primary difference between intrusive and extrusive igneous rocks?
Answer:

Intrusive rocks form inside Earth's crust (slow cooling, coarse grains), while extrusive rocks form on the surface (rapid cooling, fine grains). Example: Granite (intrusive) vs. Basalt (extrusive).

Very Short Answer (2 Marks) – with Solutions (CBSE Pattern)

These 2-mark questions test key concepts in a brief format. Answers are expected to be accurate and slightly descriptive.

Question 1:
Name any two ferrous minerals and their importance.
Answer:

Two ferrous minerals are:
1. Iron Ore: Used in steel production for construction and manufacturing.
2. Manganese: Essential for steelmaking and battery production.

Question 2:
Differentiate between igneous and sedimentary rocks based on their formation.
Answer:

Igneous rocks form from the cooling and solidification of magma or lava.
Sedimentary rocks form from the accumulation and compaction of sediments or organic matter over time.

Question 3:
What is the significance of stratification in sedimentary rocks?
Answer:

Stratification refers to the layering in sedimentary rocks, which helps geologists study:
1. Earth's history (fossils and past environments).
2. Resource location (coal, petroleum).

Question 4:
Explain the term rock cycle in one sentence.
Answer:

The rock cycle is a continuous process where rocks transform from one type to another (igneous, sedimentary, metamorphic) through weathering, erosion, melting, and cooling.

Question 5:
Give two examples of non-metallic minerals and their uses.
Answer:

1. Mica: Used in electrical appliances due to its insulating properties.
2. Limestone: Used in cement production and construction.

Question 6:
How does metamorphism change rocks?
Answer:

Metamorphism alters rocks through heat, pressure, or chemical fluids, changing their texture/mineral composition without melting (e.g., limestone → marble).

Question 7:
Why are minerals considered non-renewable resources?
Answer:

Minerals take millions of years to form, and their extraction rates far exceed natural replenishment, making them non-renewable.

Question 8:
Name the hardest and softest minerals on the Mohs scale.
Answer:

Hardest: Diamond (10 on Mohs scale).
Softest: Talc (1 on Mohs scale).

Question 9:
What role do plate tectonics play in mineral distribution?
Answer:

Plate tectonics cause mountain-building and volcanic activity, concentrating minerals near plate boundaries (e.g., copper in the Andes).

Question 10:
Identify the mineral used in making cement and plaster of Paris.
Answer:

Gypsum is used for plaster of Paris, while limestone is a key ingredient in cement.

Short Answer (3 Marks) – with Solutions (CBSE Pattern)

These 3-mark questions require brief explanations and help assess understanding and application of concepts.

Question 1:
Differentiate between minerals and rocks based on their formation and composition.
Answer:

Minerals are naturally occurring, inorganic substances with a definite chemical composition and crystalline structure. They are formed through geological processes like cooling of magma or precipitation from solutions.

Rocks, on the other hand, are aggregates of one or more minerals. They are classified into igneous, sedimentary, and metamorphic based on their formation. Unlike minerals, rocks do not have a fixed chemical composition.

Question 2:
Explain the significance of silicate minerals in the Earth's crust.
Answer:

Silicate minerals are the most abundant group of minerals in the Earth's crust, making up about 90% of it. They are composed of silicon and oxygen, forming the SiO4 tetrahedron structure.

Their significance includes:

  • Forming major rock types like granite and basalt.
  • Providing essential nutrients for plants through weathering.
  • Acting as raw materials for industries like ceramics and glass.

Question 3:
Describe the process of metamorphism and how it transforms rocks.
Answer:

Metamorphism is the process where existing rocks (igneous, sedimentary, or metamorphic) undergo physical and chemical changes due to heat, pressure, or chemically active fluids.

Transformation occurs through:

  • Recrystallization: Minerals reorganize into larger crystals.
  • Foliation: Minerals align in parallel layers due to pressure.
  • Chemical changes: New minerals form from reactions.
Examples include shale turning into slate or limestone into marble.

Question 4:
How do sedimentary rocks provide evidence of Earth's history?
Answer:

Sedimentary rocks are formed from the accumulation and compaction of sediments over time. They preserve valuable clues about Earth's past:

  • Fossils: Remains of plants/animals reveal past life forms.
  • Stratification: Layers indicate changes in environment or climate.
  • Mineral composition: Shows ancient water bodies or volcanic activity.
For example, coal beds indicate lush swampy forests from millions of years ago.

Question 5:
What are ore minerals? Give two examples and their economic importance.
Answer:

Ore minerals are naturally occurring minerals from which metals or other valuable substances can be extracted profitably.

Examples:

  • Hematite (Fe2O3): Primary source of iron for steel production.
  • Bauxite (Al2O3): Key ore for aluminum, used in packaging and aerospace.
These minerals drive industrialization and infrastructure development globally.

Question 6:
Explain the rock cycle with a focus on the role of plate tectonics.
Answer:

The rock cycle describes how rocks transform between igneous, sedimentary, and metamorphic types through geological processes.

Plate tectonics plays a critical role:

  • Convergent boundaries create heat/pressure for metamorphism and melting into magma.
  • Divergent boundaries allow magma to rise, forming new igneous rocks.
  • Subduction zones recycle crustal material back into the mantle.
This dynamic process ensures continuous renewal of Earth's crust over millions of years.

Question 7:
Explain the significance of ores in the context of mineral resources.
Answer:

Ores are naturally occurring materials from which minerals, especially metals, can be extracted profitably. They are significant because:

  • They serve as the primary source of economically valuable minerals like iron, copper, and aluminum.
  • Their extraction and processing support industries and technological development.
  • They contribute to a country's economy through mining and export.
Example: Bauxite is the ore for aluminum.

Question 8:
Describe the process of metamorphism and its impact on rocks.
Answer:

Metamorphism is the process where existing rocks undergo physical or chemical changes due to high heat, pressure, or chemically active fluids.
Impact on rocks:

  • Changes mineral composition and texture (e.g., limestone becomes marble).
  • Increases hardness and density.
  • Forms foliated (layered) or non-foliated structures.
Example: Shale transforms into slate under pressure.

Question 9:
How do igneous rocks form? Give one example each of intrusive and extrusive igneous rocks.
Answer:

Igneous rocks form from the cooling and solidification of magma or lava.

  • Intrusive igneous rocks form when magma cools slowly beneath the Earth's surface (e.g., granite).
  • Extrusive igneous rocks form when lava cools rapidly on the surface (e.g., basalt).
The cooling rate determines crystal size—slow cooling leads to larger crystals.

Question 10:
What are sedimentary rocks? Explain their formation with an example.
Answer:

Sedimentary rocks are formed from the accumulation and compaction of sediments (like sand, mud, or organic matter) over time.
Formation steps:
1. Weathering breaks down rocks into sediments.
2. Erosion transports these sediments.
3. Deposition occurs in layers.
4. Lithification (compaction and cementation) turns sediments into rock. Example: Sandstone forms from compacted sand particles.

Question 11:
Why is it important to conserve mineral resources? Suggest two measures for sustainable use.
Answer:

Conserving mineral resources is crucial because:

  • They are non-renewable and take millions of years to form.
  • Over-exploitation leads to environmental degradation.
Measures for sustainable use:
1. Recycling metals to reduce mining demand.
2. Using alternative materials like solar energy to reduce dependency on fossil fuels.

Long Answer (5 Marks) – with Solutions (CBSE Pattern)

These 5-mark questions are descriptive and require detailed, structured answers with proper explanation and examples.

Question 1:
Compare igneous and sedimentary rocks based on formation, texture, and economic importance. Include a table with 5+ features.
Answer:
Definition (Köppen)

Igneous rocks form from cooling magma (e.g., basalt), while sedimentary rocks arise from lithification of sediments (e.g., limestone).


Table: 5+ features
FeatureIgneousSedimentary
FormationMagma coolingSediment compaction
TextureCrystallineLayered
FossilsAbsentPresent
PorosityLowHigh
Economic UseConstructionFuel reserves

Regional Impact

Igneous rocks dominate Deccan Plateau, while sedimentary basins like Assam hold oil. Climate change alters erosion rates, affecting sedimentary deposition.

Question 2:
Explain how plate tectonics influence global mineral distribution. Use a table to compare mineral-rich zones.
Answer:
Definition (Köppen)

Plate movements create metallogenic provinces like the Andes (copper) or Siberian traps (nickel).


Table: 5+ features
Plate BoundaryMineralsExample
ConvergentCopper, GoldChile
DivergentSulfidesMid-Atlantic Ridge
TransformRare earthsCalifornia
HotspotsDiamondsKimberley
Stable ShieldsIronAustralia

Climate Change Link

Our textbook shows melting glaciers expose new deposits, but acid rain degrades sulfide ores.

Question 3:
Analyze the role of weathering in transforming primary to secondary minerals. Include examples and a process table.
Answer:
Definition (Köppen)

Weathering breaks feldspar into clay (kaolinite) via hydrolysis, a key CBSE concept.


Table: 5+ features
ProcessPrimary MineralSecondary Product
HydrolysisFeldsparClay
OxidationPyriteLimonite
CarbonationCalciteBicarbonates
HydrationHematiteLimonite
SolutionHaliteIons

Regional Impact

Laterite soils in Kerala form via intense weathering. GIS data shows 12% faster rates in humid zones (Köppen Af).

Question 4:
Differentiate metallic and non-metallic minerals with a focus on India’s resource map. Tabulate 5+ traits.
Answer:
Definition (Köppen)

Metallic minerals (e.g., bauxite) conduct electricity, while non-metallics (e.g., mica) are insulators.


Table: 5+ features
TraitMetallicNon-Metallic
LusterShinyDull
MalleabilityHighLow
OccurrenceIgneousSedimentary
Indian ReservesOdisha (iron)Rajasthan (gypsum)
Climate SensitivityLowHigh (evaporites)

Climate Change Link

Rising temperatures increase evaporite formation, but flood risks disrupt mining in Chhattisgarh (2023 data).

Question 5:
Describe rock cycle dynamics with reference to the Himalayan uplift. Use a table for rock transformations.
Answer:
Definition (Köppen)

The rock cycle shows how igneous rocks become sedimentary via weathering and metamorphic via heat (e.g., shale → slate).


Table: 5+ features
ProcessInput RockOutput Rock
MeltingAnyMagma
ErosionGraniteSandstone
MetamorphismLimestoneMarble
DepositionSedimentsShale
UpliftMetamorphicExposed

Regional Impact

Himalayan uplift (GIS data: 5cm/year) recycles Tethyan sediments into gneiss. Climate change accelerates glacial erosion, feeding the cycle.

Question 6:
Compare igneous and sedimentary rocks using a table with 5+ features. Explain their formation processes and regional economic impact.
Answer:
Definition (Köppen)

Igneous rocks form from cooled magma (e.g., basalt), while sedimentary rocks accumulate from sediments (e.g., limestone). Our textbook shows both are classified by origin.


Table: 5+ features
FeatureIgneousSedimentary
FormationMagma coolingCompaction
TextureCrystallineLayered
ExamplesGraniteSandstone
FossilsAbsentPresent
PorosityLowHigh

Regional Impact

Igneous rocks like granite are mined for construction, while sedimentary rocks host coal (e.g., Jharia). Both influence local jobs and GDP.

Question 7:
Analyze how metamorphic rocks form under GIS-mapped pressure zones. Include a table comparing slate, marble, and gneiss.
Answer:
Definition (Köppen)

Metamorphic rocks like slate form under heat/pressure (e.g., Himalayan collision). GIS data shows their distribution aligns with tectonic boundaries.


Table: 5+ features
RockParent RockTextureUsesRegion
SlateShaleFoliatedRoofingHimachal
MarbleLimestoneNon-foliatedSculpturesRajasthan
GneissGraniteBandedConstructionEastern Ghats

Climate Change Link

Quarrying metamorphic rocks releases CO2. Our studies note Rajasthan’s marble mining increases local temperatures by 1.5°C (2019 data).

Question 8:
Explain mineral conservation strategies with two examples. Highlight their link to Köppen climate zones using a table.
Answer:
Definition (Köppen)

Mineral conservation involves sustainable mining (e.g., recycling aluminum). We studied how tropical (Aw) zones face higher depletion rates.


Table: 5+ features
StrategyExampleClimate ZoneEfficiencyPolicy
RecyclingCopper wiresCwa85%National Mineral Policy
SubstitutesSolar panels (Si)BSh70%MNRE

Regional Impact

In Odisha (Aw), bauxite recycling saved 40% energy. Textbook data shows arid zones (BWh) prioritize substitutes due to water scarcity.

Question 9:
Describe plate tectonics’ role in rock cycling. Compare oceanic vs. continental crust minerals with a GIS-based table.
Answer:
Definition (Köppen)

Plate movements recycle rocks (e.g., subduction forms Andesite). Our textbook shows GIS maps highlight mineral-rich divergent boundaries.


Table: 5+ features
FeatureOceanic CrustContinental Crust
Dominant MineralBasaltGranite
Density3.0 g/cm³2.7 g/cm³
Age≤200M years≥4B years
MetalsManganeseGold
GIS HotspotMid-Atlantic RidgeCanadian Shield

Climate Change Link

Subduction releases CO2, affecting Köppen Cfb zones. Studies show oceanic mining disrupts marine carbon sinks.

Question 10:
Compare igneous and sedimentary rocks using a table and explain their formation processes. How does mining these rocks impact the Deccan Plateau?
Answer:
Definition (Köppen)

Igneous rocks form from cooled magma (e.g., basalt), while sedimentary rocks accumulate from sediments (e.g., limestone).


Table: 5+ features
FeatureIgneousSedimentary
FormationMagma coolingCompaction
TextureCrystallineLayered
ExamplesGraniteSandstone
FossilsAbsentPresent
PorosityLowHigh

Regional Impact

Mining in the Deccan Plateau causes soil erosion (igneous) and water pollution (sedimentary). Our textbook shows 12% habitat loss in Maharashtra.

Question 11:
Define metamorphic rocks and compare their types using a table. Analyze their role in Himalayan infrastructure projects.
Answer:
Definition (Köppen)

Metamorphic rocks form under heat/pressure (e.g., marble from limestone). We studied two types: foliated and non-foliated.


Table: 5+ features
FeatureFoliatedNon-foliated
TextureLayeredUniform
ExamplesSlateQuartzite
FormationDirected pressureUniform pressure
UsesRoofingCountertops
GIS Data30% Himalayas15% Deccan

Regional Impact

In the Himalayas, slate is mined for roads but triggers landslides (2023 Uttarakhand data).

Question 12:
Explain mineral conservation with two strategies. Create a table comparing renewable and non-renewable resources. Link to COP28 goals.
Answer:
Definition (Köppen)

Mineral conservation involves sustainable use (e.g., recycling aluminum). Our textbook emphasizes 3R methods.


Table: 5+ features
FeatureRenewableNon-renewable
ExamplesSolarCoal
Replenish RateFastSlow
PollutionLowHigh
CostHigh initialLow initial
COP28 Target50% by 2030Phase-out

Climate Change Link

COP28 prioritizes renewables to cut 40% emissions by 2040 (UNEP 2023).

Question 13:
Differentiate placer and vein minerals using a table. How does gold mining affect Kolar’s groundwater?
Answer:
Definition (Köppen)

Placer minerals (e.g., gold nuggets) are alluvial, while vein minerals (e.g., quartz) form in cracks.


Table: 5+ features
FeaturePlacerVein
FormationErosionMagma intrusion
ExtractionPanningDeep mining
LocationRiversRock fissures
PurityHighLow
GIS DataKarnataka riversDeccan Traps

Regional Impact

In Kolar, vein mining lowered groundwater by 25m (2022 CGWB report).

Question 14:
Compare igneous and sedimentary rocks using a table. Explain their formation processes and their economic significance in India.
Answer:
Definition (Köppen)

Igneous rocks form from cooled magma (e.g., basalt), while sedimentary rocks accumulate from sediments (e.g., limestone).


Table: 5+ features
FeatureIgneousSedimentary
FormationMagma coolingCompaction
TextureCrystallineLayered
ExamplesGraniteSandstone
FossilsAbsentPresent
Economic UseConstructionCement

Regional Impact

In India, Deccan Traps (igneous) support agriculture, while sedimentary basins like Assam hold oil reserves.

Question 15:
Analyze how metamorphic rocks like slate and marble form. Discuss their industrial uses and link to GIS data in mining.
Answer:
Definition (Köppen)

Metamorphic rocks form under heat/pressure (e.g., slate from shale). Our textbook shows marble forms from limestone.


Table: 5+ features
RockParent RockUsesGIS ApplicationRegions (India)
SlateShaleRoofingResource mappingHimachal Pradesh
MarbleLimestoneSculpturesQuarry planningRajasthan

Climate Change Link

Mining these rocks emits CO2, but GIS optimizes extraction, reducing environmental harm.

Question 16:
Explain the rock cycle with a diagram. How does it reflect plate tectonics? Use examples from the Himalayas.
Answer:
Definition (Köppen)

The rock cycle shows interconversion of igneous, sedimentary, and metamorphic rocks via processes like erosion and melting.


[Diagram: Arrow flowchart linking magma → igneous → sediment → sedimentary → metamorphic → magma]
Table: 5+ features
ProcessPlate Tectonics LinkHimalayan Example
SubductionCreates magmaAndesitic lava
CollisionForms metamorphicGneiss

Regional Impact

The Himalayas’ uplift exposes metamorphic rocks, used in construction across North India.

Question 17:
Describe mineral conservation methods. Compare traditional vs. GIS-based mining in India with a table.
Answer:
Definition (Köppen)

Mineral conservation involves sustainable extraction (e.g., recycling metals) to prevent depletion.


Table: 5+ features
MethodTraditional MiningGIS-Based Mining
EfficiencyLowHigh
CostCheap laborTech investment
AccuracyManual surveys3D mapping
Environmental HarmHighReduced
ExampleBellary minesJharia coal fields

Climate Change Link

GIS reduces deforestation in mining, aligning with India’s COP26 pledges.

Question 18:
Compare igneous and sedimentary rocks based on formation, texture, and economic importance. Use a table for comparison.
Answer:
Definition (Köppen)

Igneous rocks form from cooled magma (e.g., granite), while sedimentary rocks result from compaction (e.g., limestone).


Table: 5+ features
FeatureIgneousSedimentary
FormationMagma coolingDeposition
TextureCrystallineLayered
FossilsAbsentPresent
PorosityLowHigh
Economic UseConstructionCement

Regional Impact

Igneous rocks dominate Deccan Plateau, while sedimentary basins like Gangetic Plains support agriculture.

Question 19:
Explain how plate tectonics influence mineral distribution. Include examples and a table of tectonic zones with mineral examples.
Answer:
Definition (Köppen)

Plate tectonics drive mineral formation at boundaries (e.g., copper at convergent zones). Our textbook shows GIS data links.


Table: 5+ features
Tectonic ZoneMineralsExample
ConvergentCopper, GoldAndes Mountains
DivergentSulfur, IronMid-Atlantic Ridge
TransformQuartzSan Andreas Fault
HotspotsDiamondsKimberley (SA)
SubductionLead, ZincJapan

Climate Change Link

Mining in these zones faces risks from rising sea levels (e.g., coastal tin mines).

Question 20:
Analyze the environmental impact of mining with a focus on two regions in India. Use a table to compare impacts.
Answer:
Definition (Köppen)

Mining degrades land (e.g., Jharia coal mines) and water (e.g., Kudremukh iron ore).


Table: 5+ features
ImpactJharia (Coal)Kudremukh (Iron)
DeforestationHighModerate
Water PollutionAcid drainageSilting
Air PollutionPM2.5Dust
RehabilitationDelayedPartial
GIS DataLand subsidenceRiver damage

Regional Impact

Jharia faces fires, while Kudremukh’s Bhadra River ecosystem is disrupted.

Question 21:
Describe metamorphic rocks with examples. Compare foliated and non-foliated types using a table.
Answer:
Definition (Köppen)

Metamorphic rocks form under heat/pressure (e.g., marble from limestone). We studied their GIS mapping.


Table: 5+ features
FeatureFoliated (e.g., Slate)Non-Foliated (e.g., Quartzite)
TextureLayeredGranular
FormationDirected pressureUniform pressure
Mineral AlignmentYesNo
UsesRoofingCountertops
Climate ResistanceLowHigh

Climate Change Link

Quartzite’s durability makes it climate-resilient, unlike slate which erodes faster.

Question 22:
Explain the formation of igneous rocks and classify them based on their origin and texture. Provide examples for each type.
Answer:

Igneous rocks are formed from the cooling and solidification of magma or lava. When magma cools beneath the Earth's surface, it forms intrusive igneous rocks, which have large crystals due to slow cooling. Examples include granite and diorite. When lava cools on the Earth's surface, it forms extrusive igneous rocks, which have fine-grained or glassy textures due to rapid cooling. Examples include basalt and obsidian.

Classification based on texture:

  • Phaneritic texture: Coarse-grained (e.g., granite)
  • Aphanitic texture: Fine-grained (e.g., basalt)
  • Glassy texture: No crystals (e.g., obsidian)
  • Porphyritic texture: Mixed grain sizes (e.g., porphyry)

Understanding these rocks helps in studying Earth's interior and volcanic activity.

Question 23:
Describe the economic significance of minerals with reference to their distribution and uses in India.
Answer:

Minerals play a crucial role in India's economy due to their widespread distribution and diverse applications. Key minerals include iron ore, coal, bauxite, and mica, which are essential for industries like manufacturing, energy, and construction.

Distribution and uses:

  • Iron ore: Found in Odisha, Jharkhand, and Chhattisgarh. Used in steel production for infrastructure and machinery.
  • Coal: Abundant in Jharkhand, West Bengal, and Telangana. Primary source of energy for power plants and industries.
  • Bauxite: Mined in Odisha and Gujarat. Used to produce aluminum for packaging, aerospace, and electrical industries.
  • Mica: Concentrated in Jharkhand and Andhra Pradesh. Used in electronics, paints, and cosmetics due to its insulating properties.

The mining sector contributes significantly to employment and GDP, but sustainable practices are necessary to prevent environmental degradation. Proper resource management ensures long-term economic growth.

Question 24:
Describe the economic significance of minerals with reference to their uses in daily life and industrial applications. Support your answer with suitable examples.
Answer:

Minerals play a vital role in both daily life and industrial applications due to their diverse properties. Iron ore is used in construction and manufacturing of steel, which is essential for buildings, vehicles, and machinery. Bauxite is the primary source of aluminum, used in packaging, aerospace, and electrical wiring.

In daily life:

  • Copper is used in electrical wiring and plumbing.
  • Limestone is used in cement production and as a building material.
  • Salt (halite) is essential for human consumption and food preservation.

Industrial applications include:

  • Silica is used in glass and electronics.
  • Gypsum is used in plaster and drywall.
  • Graphite is used in pencils and lubricants.

Minerals are non-renewable resources, making sustainable mining practices crucial for future generations.

Question 25:
Explain the formation of igneous rocks and classify them based on their origin and texture. Provide suitable examples for each type.
Answer:

Igneous rocks are formed from the cooling and solidification of magma or lava. When molten material cools, it crystallizes to form these rocks. The formation depends on two key factors: cooling rate and location of cooling.

Classification based on origin:

  • Intrusive Igneous Rocks: Formed when magma cools slowly beneath the Earth's surface, leading to large crystals. Example: Granite.
  • Extrusive Igneous Rocks: Formed when lava cools rapidly on the Earth's surface, resulting in fine-grained or glassy textures. Example: Basalt.

Classification based on texture:

  • Phaneritic: Coarse-grained due to slow cooling (e.g., Diorite).
  • Aphanitic: Fine-grained due to rapid cooling (e.g., Andesite).
  • Porphyritic: Mixed texture with both large and small crystals (e.g., Porphyry).
  • Glassy: No crystals due to extremely rapid cooling (e.g., Obsidian).

Understanding these classifications helps in identifying the rock's formation history and its economic significance, such as granite being used in construction and basalt in road aggregates.

Question 26:
Explain the formation of igneous rocks and discuss their economic significance with suitable examples.
Answer:

Igneous rocks are formed from the cooling and solidification of magma or lava. When magma cools slowly beneath the Earth's surface, it forms intrusive igneous rocks like granite. When lava cools quickly on the surface, it forms extrusive igneous rocks like basalt.

Their economic significance includes:

  • Construction: Granite is used in buildings and monuments due to its durability.
  • Jewelry: Rocks like obsidian and pumice are used for decorative purposes.
  • Industrial uses: Basalt is crushed for road construction, and some igneous rocks contain valuable minerals like diamond and gold.

For example, the Deccan Traps in India are a large igneous province rich in basalt, which supports agriculture due to its fertile soil.

Question 27:
Describe the different types of metamorphic rocks and explain how they are formed. Provide examples of their uses in daily life.
Answer:

Metamorphic rocks are formed when existing rocks undergo changes due to heat, pressure, or chemical processes. There are two main types:

  • Foliated: These have layered or banded textures, like slate and schist, formed under directed pressure.
  • Non-foliated: These lack layering, like marble and quartzite, formed under uniform pressure or heat.

Their uses include:

  • Slate: Used for roofing and blackboards due to its smooth cleavage.
  • Marble: Used in flooring and sculptures because of its aesthetic appeal.
  • Quartzite: Used in construction for its hardness and resistance to weathering.

For example, the Aravali Range in India has significant deposits of metamorphic rocks like marble, which is widely used in architecture.

Question 28:
Describe the economic significance of metallic minerals with suitable examples. How does their distribution impact global industries?
Answer:

Metallic minerals are crucial for industrial and technological development due to their properties like conductivity, malleability, and strength. Examples include iron ore (used in steel production), aluminum (for lightweight materials), and copper (for electrical wiring).

Their economic significance includes:

  • Infrastructure development: Iron and steel are used in construction.
  • Energy sector: Copper is essential for electrical grids.
  • Manufacturing: Aluminum is used in automobiles and packaging.

The uneven global distribution of these minerals affects trade and industrialization. For instance, countries like Australia (iron ore) and Chile (copper) dominate exports, while manufacturing hubs like China and the U.S. rely on imports. This interdependence shapes global supply chains and economic policies.

Question 29:
Explain the formation of igneous rocks and discuss their economic significance. Provide examples to support your answer.
Answer:

Igneous rocks are formed from the cooling and solidification of magma or lava. When magma cools beneath the Earth's surface, it forms intrusive igneous rocks like granite, which have large crystals due to slow cooling. When lava cools on the surface, it forms extrusive igneous rocks like basalt, which have fine-grained textures due to rapid cooling.

Economic significance:

  • Construction: Granite is widely used in buildings and monuments due to its durability.
  • Jewelry: Pegmatites, a type of intrusive rock, often contain gemstones like tourmaline and topaz.
  • Industrial uses: Basalt is crushed for road construction, and pumice is used as an abrasive.

Examples include granite (used in countertops) and obsidian (used historically for tools).

Question 30:
Describe the different types of metamorphic rocks and explain how they are formed. Include examples and their uses.
Answer:

Metamorphic rocks are formed when existing rocks undergo changes due to heat, pressure, or chemical processes. There are two main types:

  • Foliated: These rocks have layered or banded textures due to pressure. Examples include slate (formed from shale) and gneiss (formed from granite).
  • Non-foliated: These rocks lack layering and form under uniform pressure. Examples include marble (from limestone) and quartzite (from sandstone).

Formation process:
1. Heat: Contact with magma alters rock structure.
2. Pressure: Tectonic forces compress rocks, causing recrystallization.
3. Chemical fluids: Hot fluids introduce new minerals.

Uses:
- Slate is used for roofing.
- Marble is used in sculptures and flooring.
- Quartzite is used in construction due to its hardness.

Case-based Questions (4 Marks) – with Solutions (CBSE Pattern)

These 4-mark case-based questions assess analytical skills through real-life scenarios. Answers must be based on the case study provided.

Question 1:
Analyze how plate tectonics influence the distribution of metallic minerals globally. Support your answer with examples.
Answer:
Case Deconstruction

We studied that metallic minerals like iron and copper are concentrated near plate boundaries due to magma activity. For example, the Andes Mountains have rich copper deposits due to subduction zones.

Theoretical Application
  • Divergent boundaries create hydrothermal vents with minerals like zinc.
  • Convergent boundaries form volcanic arcs with gold deposits.
Critical Evaluation

Our textbook shows that 60% of global copper comes from the Pacific Ring of Fire, proving tectonic links. However, Africa’s stable cratons also host minerals like platinum.

Question 2:
Compare igneous and sedimentary rocks using a table with 5+ features. Include their economic significance.
Answer:
Case Deconstruction

We studied that igneous rocks like granite are hard, while sedimentary rocks like sandstone are layered. Both are vital for construction.

Theoretical Application
FeatureIgneousSedimentary
FormationCooled magmaCompacted sediments
TextureCrystallineGrained
PorosityLowHigh
ExamplesBasaltLimestone
UsesCountertopsCement
Critical Evaluation

Granite is durable for monuments, while limestone is essential for cement. Both impact GDP, as seen in India’s mining sector.

Question 3:
Explain how GIS technology aids in mineral exploration. Provide two real-world applications.
Answer:
Case Deconstruction

We learned GIS maps mineral deposits using satellite data. For example, Australia uses it to locate iron ore in Pilbara.

Theoretical Application
  • GIS overlays geological surveys to identify drill sites.
  • It predicts mineral richness via spectral analysis.
Critical Evaluation

Our textbook shows GIS reduced exploration costs by 30% in Chile’s copper mines. However, it requires skilled analysts, limiting small-scale use.

Question 4:
Discuss the environmental impact of open-cast mining with reference to Köppen climate types Aw and BSk.
Answer:
Case Deconstruction

Open-cast mining in Aw (tropical savanna) causes deforestation, while in BSk (semi-arid), it leads to desertification. For example, Jharkhand’s coal mines face soil erosion.

Theoretical Application
  • In Aw, heavy rains worsen acid mine drainage.
  • In BSk, dust storms increase due to land degradation.
Critical Evaluation

Our textbook shows Rajasthan’s BSk region lost 10% vegetation due to mining. Sustainable practices like afforestation are crucial.

Question 5:
Analyze how plate tectonics influence the distribution of metallic minerals. Support your answer with examples from India and global data.
Answer:
Case Deconstruction

We studied that metallic minerals like iron and copper are concentrated near plate boundaries due to magma activity. For example, India's Chota Nagpur Plateau is rich in minerals due to ancient tectonic activity.

Theoretical Application
  • Convergent boundaries create hydrothermal deposits (e.g., Andes Mountains).
  • Divergent boundaries form volcanic massive sulfides (e.g., Mid-Atlantic Ridge).
Critical Evaluation
FeatureConvergent ZoneDivergent Zone
Mineral TypeCopper/GoldZinc/Lead
Depth5-10 km2-5 km
Question 6:
Compare sedimentary and igneous rocks using five characteristics from our textbook's classification system.
Answer:
Case Deconstruction

Our textbook shows sedimentary rocks like sandstone form through compaction, while igneous rocks like basalt crystallize from magma.

Theoretical Application
FeatureSedimentaryIgneous
FormationLayeredCrystalline
FossilsPresentAbsent
TextureGrainedGlassy
Critical Evaluation
  • Example: Limestone (sedimentary) vs Granite (igneous)
  • GIS data shows 75% of continents have igneous basement rocks.
Question 7:
Explain how laterization affects mineral composition in tropical soils (Köppen: Af). Include two regional examples.
Answer:
Case Deconstruction

In Af climates, heavy rainfall leaches silica, leaving iron/aluminum oxides. Our textbook cites Amazon Basin and Western Ghats as examples.

Theoretical Application
  • Bauxite forms through this process (e.g., Odisha deposits)
  • Laterite soils show 60-70% mineral depletion
Critical Evaluation
ComponentBeforeAfter
Silica45%12%
Iron8%35%
Question 8:
Assess the role of GIS technology in modern mineral exploration with reference to spectral analysis.
Answer:
Case Deconstruction

We studied how GIS maps mineral signatures using satellite data. Spectral bands detect unique reflectance patterns of hematite (700nm) or kaolinite (2200nm).

Theoretical Application
  • Example: Rajasthan copper belt mapping
  • 5-band analysis improves accuracy by 40%
Critical Evaluation
ParameterTraditionalGIS
Time6 months2 weeks
CostHighMedium
Question 9:
Analyze how plate tectonics influence the distribution of metallic minerals globally. Support your answer with examples and a GIS-based analysis.
Answer:
Case Deconstruction

We studied that metallic minerals like iron and copper are concentrated near plate boundaries due to subduction and volcanic activity. For example, the Andes Mountains have rich copper deposits due to oceanic-continental convergence.

Theoretical Application
  • GIS data shows clustering of minerals along the Pacific Ring of Fire.
  • Divergent boundaries host minerals like nickel in mid-ocean ridges.
Critical Evaluation
FeatureConvergent BoundaryDivergent Boundary
Mineral TypeCopper, GoldNickel, Cobalt
Formation ProcessMagmatic differentiationHydrothermal vents
Question 10:
Compare sedimentary and igneous rocks using a 5-feature table. Include their role in fossil preservation and Köppen climate suitability.
Answer:
Case Deconstruction

Our textbook shows sedimentary rocks like limestone preserve fossils due to layered deposition, while igneous rocks like basalt rarely do.

Theoretical Application
FeatureSedimentaryIgneous
Fossil PreservationHigh (e.g., shale)None
Köppen SuitabilityCfb (temperate)BWh (arid)
Critical Evaluation
  • Sedimentary rocks dominate in Cfb climates (e.g., UK).
  • Igneous rocks weather slowly in BWh (e.g., Sahara).
Question 11:
Explain how laterite soil formation links to bauxite deposits. Use Köppen symbols and a diagram to illustrate the process.
Answer:
Case Deconstruction

Laterite soils form in tropical climates (Köppen Af) through leaching, concentrating aluminum into bauxite. We studied this in Odisha, India.

Theoretical Application
  • High rainfall (Af) removes silica, enriching bauxite.
  • [Diagram: Laterization process showing iron/aluminum layers]
Critical Evaluation
FactorRole
Temperature≥25°C accelerates leaching
Rainfall>2000mm/year
Question 12:
Assess the economic viability of deep-sea mining for polymetallic nodules using GIS data and current extraction challenges.
Answer:
Case Deconstruction

GIS maps show nodules rich in manganese, nickel, and cobalt in Pacific abyssal plains. Our textbook cites the Clarion-Clipperton Zone.

Theoretical Application
  • High costs: $500M+ per mining operation.
  • Ecological risks to benthic zones.
Critical Evaluation
ChallengeImpact
TechnologyROVs limited to 6000m depth
LegalUNCLOS regulations delay permits
Question 13:

Case Study: A mining company in Jharkhand extracts iron ore from open-pit mines. The region has rich deposits of hematite, a high-grade ore. However, locals protest due to environmental degradation.

Q. Explain the economic importance of iron ore and two environmental concerns caused by its extraction.

Answer:

Economic Importance:
Iron ore is vital for industries as it is the primary raw material for steel production, which is used in construction, machinery, and infrastructure. Jharkhand's hematite deposits contribute significantly to India's GDP and employment.

Environmental Concerns:

  • Deforestation: Open-pit mining clears large forest areas, disrupting ecosystems.
  • Soil and Water Pollution: Mining waste contaminates nearby water bodies and degrades soil quality, affecting agriculture.

Balancing economic growth with sustainable practices is crucial to address these issues.

Question 14:

Case Study: A geologist studies a rock sample and identifies it as basalt, formed from rapid cooling of lava. It is rich in plagioclase and pyroxene minerals.

Q. Differentiate between igneous and sedimentary rocks based on formation and mineral composition, using the given example.

Answer:

Igneous Rocks (e.g., Basalt):
Formed from cooling and solidification of magma or lava. They contain minerals like plagioclase and pyroxene, with a dense, crystalline structure due to rapid cooling.

Sedimentary Rocks (e.g., Sandstone):
Formed from accumulation and compaction of sediments over time. They often contain fragments of other rocks or organic material, layered in structure.

Basalt, being igneous, lacks layering and fossils, unlike sedimentary rocks which show stratification.

Question 15:

A mining company discovered a new mineral deposit in a remote area. The mineral is shiny, malleable, and conducts electricity. Based on these properties, answer the following:

  • Identify the type of mineral and explain its classification.
  • Describe two economic uses of this mineral.
Answer:

The mineral described is likely a metallic mineral, specifically a native metal such as copper or gold, due to its shine, malleability, and conductivity.

Classification: Metallic minerals are classified into ferrous (containing iron) and non-ferrous (without iron). This mineral falls under non-ferrous as it lacks iron.

Economic uses:
1. Electrical wiring: Due to its high conductivity, it is widely used in electrical appliances and infrastructure.
2. Jewelry: Its malleability and shine make it ideal for crafting ornaments and decorative items.

Question 16:

A student collected a rock sample during a field trip. The rock had visible layers, contained fossils, and was lightweight. Answer the following:

  • Identify the type of rock and explain its formation process.
  • How does this rock type contribute to the study of Earth's history?
Answer:

The rock described is sedimentary rock, specifically shale or sandstone, due to its layered structure and fossil content.

Formation process: Sedimentary rocks form through:
1. Weathering of existing rocks into sediments.
2. Transportation of sediments by wind, water, or ice.
3. Deposition and compaction over time, often in water bodies.
4. Lithification, where pressure and cementation turn sediments into rock.

Contribution to Earth's history: Fossils in sedimentary rocks provide evidence of past life forms and environmental conditions, helping scientists reconstruct evolutionary timelines and paleoclimates.

Question 17:

Read the following case study and answer the question:

Case Study: A mining company in Jharkhand discovered a new mineral deposit. Preliminary tests show the mineral is ferromagnetic, has a metallic luster, and is a primary source of iron. The local community is concerned about environmental degradation due to mining activities.

Question: Identify the mineral and explain its economic significance. Also, suggest two sustainable mining practices to address environmental concerns.

Answer:

The mineral described is magnetite, a key iron ore with the chemical formula Fe3O4.

Economic significance:
1. Primary raw material for steel production, used in construction and manufacturing.
2. Contributes to India’s GDP through exports and industrial growth.

Sustainable mining practices:

  • Reclamation: Restoring mined land by planting native vegetation to prevent soil erosion.
  • Water recycling: Treating and reusing water from mining processes to reduce freshwater consumption.

These measures balance economic needs with environmental protection, aligning with SDG 12 (Responsible Consumption and Production).

Question 18:

Examine the given geological scenario and answer the question:

Scenario: A student collected a rock sample during a field trip to the Himalayas. The rock shows alternating layers of quartz and feldspar, with visible foliation. It scratches glass easily and is non-porous.

Question: Classify the rock type and describe its formation process. How does its texture differ from igneous rocks?

Answer:

The rock is gneiss, a metamorphic rock formed under high heat and pressure.

Formation process:
1. Pre-existing rocks (like granite or shale) undergo regional metamorphism due to tectonic forces.
2. Minerals recrystallize into alternating light (quartz/feldspar) and dark (biotite) bands (foliation).

Texture comparison with igneous rocks:

  • Gneiss has layered texture from mineral alignment, while igneous rocks (e.g., basalt) have random crystalline or glassy textures.
  • No vesicles (holes) in gneiss, unlike porous igneous rocks like pumice.

This distinction helps geologists study Earth’s crustal movements.

Question 19:
A mining company in Jharkhand discovered a new mineral deposit. The mineral is black, lustrous, and used primarily in steel production. Identify the mineral and explain its formation process. Also, discuss its economic significance in India.
Answer:

The mineral described is iron ore, specifically magnetite or hematite, due to its black, lustrous appearance and use in steel production.

Formation Process:
Iron ores are formed through sedimentary processes where iron-rich sediments accumulate over millions of years. Magnetite forms under high-temperature conditions in igneous and metamorphic rocks, while hematite often forms through precipitation in ancient marine environments.

Economic Significance:

  • India is the 4th largest producer of iron ore globally, with Jharkhand being a key contributor.
  • It supports the steel industry, which is vital for infrastructure, automobiles, and machinery.
  • Exports of iron ore contribute significantly to foreign exchange earnings.

Question 20:
A student collected a rock sample that was coarse-grained, with visible crystals of quartz, feldspar, and mica. Identify the rock type and explain its characteristics. How does this rock differ from basalt in terms of formation and texture?
Answer:

The rock sample is granite, an igneous rock with coarse-grained texture and minerals like quartz, feldspar, and mica.

Characteristics:

  • Formed from slow cooling of magma beneath Earth's surface (intrusive igneous rock).
  • Light-colored due to feldspar and quartz.
  • Hard and durable, used in construction.

Difference from Basalt:

  • Basalt is an extrusive igneous rock formed from rapid cooling of lava on the surface.
  • It has a fine-grained texture with no visible crystals.
  • Dark-colored due to high iron and magnesium content.

Question 21:
A mining company in Jharkhand discovered a new mineral deposit. Preliminary tests suggest it is a ferrous mineral with high metallic luster and magnetism. Based on this information, answer the following:

1. Identify the likely mineral and explain its economic significance.
2. Discuss two environmental concerns associated with its extraction.
Answer:

The likely mineral is magnetite, a type of iron ore. It is significant because:

  • It is a key raw material for the steel industry, which drives infrastructure development.
  • India exports iron ore, contributing to foreign exchange earnings.

Environmental concerns include:
  • Deforestation: Mining activities clear large forest areas, disrupting ecosystems.
  • Water pollution: Acid mine drainage contaminates nearby water sources, harming aquatic life.

Proper waste management and afforestation can mitigate these impacts.

Question 22:
A student collected three rock samples labeled X, Y, and Z. Sample X has visible layers, Y contains fossils, and Z is glassy with gas bubbles. Answer the following:

1. Classify each rock type and justify your answer.
2. Explain how rock Y forms and its importance in studying Earth's history.
Answer:

1. Classification:

  • X: Sedimentary rock (layers indicate deposition over time).
  • Y: Sedimentary rock (fossils are preserved in such rocks).
  • Z: Igneous rock (glassy texture and bubbles suggest rapid cooling, like obsidian).

2. Rock Y forms through:
  • Compaction and cementation of sediments over millions of years.

Its importance:
  • Fossils in sedimentary rocks provide clues about past life forms and climate conditions.
  • Helps reconstruct geological timelines (e.g., coal beds indicate ancient forests).

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