Lesson Notes By Weeks and Term v3 - Senior Secondary 3
Physical and Chemical Properties of Rock-Forming Mineral
Download the Lessonotes Mobile Nigeria 2025 app for faster lesson access on Android and iPhone.
Physical and Chemical Properties of Rock-Forming Mineral
Download the Lessonotes Mobile Nigeria 2025 app for faster lesson access on Android and iPhone.
Subject: Mining
Class: Senior Secondary 3
Term: 2nd Term
Week: 1
Theme: Basic Geology
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
Name the rock-for ming minerals Classify the rock-for ming minerals based on the ir crystal for ms and chemistry.
base metal deposits.
3. Oxides: Minerals where a metal is bonded with oxygen.
Formula: MxOγ.
Examples: Hematite (Fe2O3), Magnetite (Fe3O4), Cassiterite (SnO2), Bauxite (Al(OH)3 - technically a hydroxide, but often grouped with oxides).
Nigerian Context: Hematite and Magnetite are major iron ores (e.g., Itakpe iron ore). Cassiterite is the primary ore for tin in Nigeria (Jos Plateau). Bauxite laterites are found in some regions.
4. Halides: Minerals where a metal is bonded with a halogen element (Fluorine, Chlorine, Bromine, Iodine).
Formula: MxXγ (X = halogen).
Examples: Halite (NaCl), Fluorite (CaF2).
Nigerian Context: Halite (rock salt) deposits exist in sedimentary basins.
5. Carbonates: Minerals containing the carbonate anion group (CO3)2−.
Formula: Mx(CO3)γ.
Examples: Calcite (CaCO3), Dolomite (CaMg(CO3)2).
Nigerian Context: Calcite is abundant in limestone deposits across Nigeria, vital for cement production. Dolomite is also present in some sedimentary and metamorphic formations.
6. Sulfates: Minerals containing the sulfate anion group (SO4)2−.
Formula: Mx(SO4)γ.
Examples: Gypsum (CaSO4·2H2O), Barite (BaSO4).
Nigerian Context: Gypsum deposits are found in states like Gombe, Benue, and Sokoto. Barite is mined in Benue, Nasarawa, Cross River, and other states, used as a drilling mud additive.
7. Phosphates: Minerals containing the phosphate anion group (PO4)3−.
Formula: Mx(PO4)γ.
Examples: Apatite (Ca5(PO4)3(F,Cl,OH)).
Nigerian Context: Apatite is an accessory mineral in some igneous and metamorphic rocks.
8. Silicates: As previously mentioned, this is the most diverse and abundant group, based on the silicon-oxygen tetrahedron (SiO4)4−. They are further subdivided based on how these tetrahedra link together: Nesosilicates (Island Silicates): Tetrahedra are isolated, bonded to cations.
Examples: Olivine, Garnet, Topaz, Zircon.
Sorosilicates (Double Island Silicates): Two tetrahedra share one oxygen atom.
Examples: Epidote.
Cyclosilicates (Ring Silicates): Tetrahedra form rings (e.g., 3-, 4-, or 6-membered rings).
Examples: Tourmaline, Beryl.
Inosilicates (Chain Silicates): Tetrahedra link to form single or double chains.
Single Chain: Pyroxene group (e.g., Augite).
Double Chain: Amphibole group (e.g., Hornblende).
Phyllosilicates (Sheet Silicates): Tetrahedra link to form continuous sheets. Characterized by perfect cleavage.
Examples: Mica group (Muscovite, Biotite), Clay minerals (Kaolinite, Montmorillonite).
Nigerian Context: Clay minerals are very important for ceramic industries and lateritic soils.
Tectosilicates (Framework Silicates): All oxygen atoms are shared, forming a complex 3D framework. *
Examples: Quartz, Feldspar group (Orthoclase, Plagioclase).
Worked Example 1: Mineral Identification in a Nigerian Context Scenario: A mining exploration team working in the Jos Plateau discovers a mineral with a distinct metallic luster, brassy yellow color, and cubic crystal forms. When scratched with a steel nail, it leaves a greenish-black streak.
Task: a. Name this mineral. b. To which chemical class does it belong? c. To which crystal system does it belong?
Solution: a.
Name: The description (metallic luster, brassy yellow, cubic crystals, greenish-black streak) strongly matches Pyrite. (Often mistaken for gold, hence "fool's gold," but gold is softer and has a yellow streak). b.
Chemical Class: Pyrite has the chemical formula FeS
2. It contains sulfur bonded with a metal (iron).
Therefore, it belongs to the Sulfide class. c.
Crystal System: The presence of distinct cubic crystal forms indicates that Pyrite belongs to the Isometric (Cubic) crystal system.
Worked Example 2: Classifying a Common Rock-Forming Mineral Scenario: A geologist examining a granite outcrop near Abeokuta, Ogun State, identifies a light-coloured mineral that breaks into thin, flexible sheets. Its chemical analysis shows significant amounts of potassium, aluminum, silicon, and oxygen.
Task: a. Suggest the likely name of this mineral. b. Based on its chemical composition, which silicate subgroup does it belong to? c. What is its typical crystal system?
Solution: a.
Likely Name: The description "light-coloured," "breaks into thin, flexible sheets," and containing potassium, aluminum, silicon, and oxygen strongly suggests Muscovite (a type of mica). b.
Silicate Subgroup (Chemistry): Muscovite's chemical formula is KAl2(AlSi3O10)(OH)
2. It is characterized by its sheet-like structure, where silicon-oxygen tetrahedra are linked to form continuous sheets.
Therefore, it belongs to the Phyllosilicates (Sheet Silicates) subgroup. c.
Typical Crystal System: Micas like Muscovite typically crystallize in the Monoclinic crystal system, often forming pseudohexagonal plates. mutually perpendicular (at 90°).
Symmetry: Highest degree of symmetry.
Common Forms: Cube, octahedron, dodecahedron, pyritohedron.
Examples: Halite (NaCl), Galena (PbS), Pyrite (FeS2), Garnet.
Nigerian Context: Galena is found in lead-zinc deposits in states like Benue and Ebonyi.
2. Tetragonal System: Axes: Three mutually perpendicular axes; two horizontal axes are of equal length, the vertical axis is either longer or shorter.
Symmetry: One principal axis of four-fold rotational symmetry.
Common Forms: Square prisms, pyramids.
Examples: Zircon (ZrSiO4), Chalcopyrite (CuFeS2).
Nigerian Context: Zircon is an accessory mineral in granites and pegmatites, found in various areas including the Younger Granites of Jos Plateau.
3. Orthorhombic System: Axes: Three mutually perpendicular axes, all of unequal length.
Symmetry: Three mutually perpendicular two-fold rotation axes.
Common Forms: Rhombic prisms, pyramids.
Examples: Olivine ((Mg,Fe)2SiO4), Topaz (Al2SiO4(F,OH)2), Barite (BaSO4).
Nigerian Context: Olivine is present in basic igneous rocks in regions like the Benue Trough. Barite is mined in Benue and other states.
4. Hexagonal System: Axes: Four axes; three horizontal axes of equal length intersecting at 120°, and a vertical axis of a different length, perpendicular to the others.
Symmetry: One principal axis of six-fold rotational symmetry.
Common Forms: Six-sided prisms, pyramids, pinacoids.
Examples: Beryl (Be3Al2Si6O18), Apatite (Ca5(PO4)3(F,Cl,OH)).
5. Trigonal System: Axes: Often grouped with hexagonal (some texts treat it as a subsystem). Three horizontal axes of equal length intersecting at 120°, and a vertical axis of a different length, perpendicular to the others. Differs in symmetry (three-fold rotational symmetry).
Symmetry: One principal axis of three-fold rotational symmetry.
Common Forms: Rhombohedra, trigonal prisms, pyramids.
Examples: Quartz (SiO2), Calcite (CaCO3), Tourmaline.
Nigerian Context: Quartz is ubiquitous. Calcite is the primary mineral in Nigerian limestones (e.g., Ewekoro, Nkalagu) used for cement production. Tourmaline is found in pegmatites.
6. Monoclinic System: Axes: Three axes of unequal length; two are inclined to each other (not at 90°), and the third is perpendicular to the other two.
Symmetry: One two-fold rotation axis or one mirror plane perpendicular to a two-fold axis.
Common Forms: Prisms, pinacoids, domes.
Examples: Orthoclase (K-feldspar), Muscovite (mica), Gypsum (CaSO4·2H2O), Hornblende.
Nigerian Context: Orthoclase and Muscovite are common in granitic rocks across Nigeria. Gypsum deposits occur in sedimentary basins.
7. Triclinic System: Axes: Three axes of unequal length, none of which are perpendicular to each other.
Symmetry: Lowest degree of symmetry (only a center of inversion, or no symmetry at all other than a 1-fold rotation axis).
Common Forms: Highly asymmetric, often appearing "messy" without clear forms.
Examples: Plagioclase feldspar (Albite, Anorthite series), Kyanite (Al2SiO5).
Nigerian Context: Plagioclase feldspar is a major constituent of many Nigerian igneous and metamorphic rocks. 2.
4. Classification based on Chemistry (Chemical Composition) Minerals are broadly classified into groups based on their dominant anionic (negatively charged) group. This is the most widely accepted and geologically significant classification.
1. Native Elements: Minerals composed of a single element.
Examples: Gold (Au), Silver (Ag), Copper (Cu), Sulfur (S), Graphite (C), Diamond (C).
Nigerian Context: Gold is mined in several parts of Nigeria (e.g., Osun, Kaduna, Zamfara). Diamond occurrences are noted in some areas.
2. Sulfides: Minerals where sulfur is bonded with a metal, excluding oxygen. Often important ore minerals.
Formula: MxSγ (M = metal).
Examples: Pyrite (FeS2), Galena (PbS), Sphalerite (ZnS), Chalcopyrite (CuFeS2).
Nigerian Context: Galena and sphalerite are significant in the lead-zinc belts of the Benue Trough. Chalcopyrite is found in some base metal deposits.
3. Oxides: Minerals where a metal is bonded with oxygen.
Formula: MxOγ.
Examples: Hematite (Fe2O3), Magnetite (Fe3O4), Cassiterite (SnO2), Bauxite (Al(OH)3 - technically a hydroxide, but often grouped with oxides).
Nigerian Context: Hematite and Magnetite are major iron ores (e.g., Itakpe iron ore). Cassiterite is the primary ore for tin in Nigeria (Jos Plateau). Bauxite laterites are found in some regions.
4. Halides: Minerals where a metal is bonded with a halogen element (Fluorine, Chlorine, Bromine, Iodine).
Formula: MxXγ (X = halogen). * This section provides detailed explanations of core concepts related to rock-forming minerals, including their definition, major types, and classification based on crystal form and chemistry. 2.
1. Definition of a Mineral A mineral is a naturally occurring, inorganic solid, with a definite chemical composition and an ordered atomic arrangement (crystalline structure).
Naturally occurring: Formed by natural geological processes, not synthetic.
Inorganic: Not formed from organic remains or processes (though some exceptions exist, e.g., coal is technically organic but often studied in geology).
Solid: Maintains a definite shape and volume under normal Earth surface conditions.
Definite chemical composition: Can be expressed by a chemical formula (e.g., Quartz is SiO2, Calcite is CaCO3). This composition can vary within certain limits, forming solid solutions. Ordered atomic arrangement (Crystalline Structure): Atoms are arranged in a specific, repeating pattern, forming a crystal lattice. This internal structure often dictates the external crystal form. 2.
2. Rock-Forming Minerals Rock-forming minerals are the relatively few minerals that make up the vast majority of the Earth's crust and thus form most rocks. While thousands of minerals exist, about 20-30 are common rock-formers. Understanding these is fundamental to geological studies and mining practices.
Common Rock-Forming Minerals: Silicates: These are the most abundant group, making up over 90% of the Earth's crust. They all contain silicon and oxygen, primarily as the silicon-oxygen tetrahedron (SiO4)4− unit.
Quartz (SiO2): Very common, hard, vitreous luster. Found in granite, sandstone, quartzite. Used in glass, electronics, and abrasives.
Feldspar Group: Most abundant mineral group.
Orthoclase (KAlSi3O8): Potassium feldspar, typically pink or white, two cleavage directions at 90°. Common in granites.
Plagioclase (NaAlSi3O8 - CaAl2Si2O8): Sodium-calcium feldspar series, typically white to grey, often shows striations on cleavage surfaces. Common in igneous and metamorphic rocks.
Mica Group: Characterized by perfect basal cleavage, allowing them to split into thin, flexible sheets.
Muscovite (KAl2(AlSi3O10)(OH)2): Light-coloured or clear mica. Biotite (K(Mg,Fe)3(AlSi3O10)(OH)2): Dark-coloured (black/dark brown) mica. Amphibole Group (e.g., Hornblende - complex silicate): Dark, elongated prismatic crystals, two cleavage directions at 56° and 124°. Common in intermediate to mafic igneous rocks. Pyroxene Group (e.g., Augite - complex silicate): Dark, short prismatic crystals, two cleavage directions at 90°. Common in mafic igneous rocks. Olivine ((Mg,Fe)2SiO4): Olive-green, granular appearance, no cleavage. Found in ultramafic rocks like peridotite. Garnet (e.g., Almandine - Fe3Al2(SiO4)3): Various colours, typically forms dodecahedral crystals, no cleavage. Found in metamorphic rocks.
Non-Silicates: Other important rock-forming minerals not based on the SiO4 tetrahedron.
Calcite (CaCO3): White or clear, effervesces with acid, perfect rhombohedral cleavage. Main mineral in limestone and marble.
Dolomite (CaMg(CO3)2): Similar to calcite but reacts weakly or not at all with cold dilute HCl. Main mineral in dolostone. Gypsum (CaSO4·2H2O): Soft (H=2), can be scratched with a fingernail, often forms tabular or fibrous crystals. Used in plaster, drywall.
Halite (NaCl): Rock salt, salty taste, perfect cubic cleavage.
Hematite (Fe2O3): Reddish-brown streak, metallic to earthy luster, primary iron ore.
Magnetite (Fe3O4): Magnetic, black, metallic luster, another important iron ore.
Pyrite (FeS2): "Fool's gold," metallic brassy yellow, cubic crystals.
Galena (PbS): Lead-grey, metallic luster, perfect cubic cleavage, lead ore. 2.
3. Classification based on Crystal Forms (Crystallography) The external shape of a mineral crystal, its crystal form, reflects the internal ordered arrangement of its atoms. Minerals are classified into seven crystal systems based on the symmetry elements (axes of rotation, planes of symmetry, center of inversion) and the relative lengths and angular relationships of their crystallographic axes.
1. Isometric System (Cubic): Axes: Three axes of equal length, mutually perpendicular (at 90°).
Symmetry: Highest degree of symmetry.
Common Forms: Cube, octahedron, dodecahedron, pyritohedron.
Examples: Halite (NaCl), Galena (PbS), Pyrite (FeS2), Garnet.
Nigerian Context: Galena is found in lead-zinc deposits in states like Benue and Ebonyi.
2. Tetragonal System: Axes: Three mutually perpendicular axes; two horizontal axes are of equal length, the vertical axis is either longer or shorter.
Symmetry: One principal axis of four-fold rotational symmetry.
Common Forms: Square prisms, pyramids.
Examples: Zircon (ZrSiO4), Chalcopyrite (CuFeS2).
Nigerian Context: Zircon is This section outlines practical activities for both the teacher and students to facilitate understanding and engagement. 3.
1. Teacher Activities: Introduction (10 minutes): Begin by eliciting students' prior knowledge of rocks and minerals.
Ask questions like: "What are rocks made of?" "Can you name any minerals?" Display various mineral samples (if available) or high-quality pictures of common rock-forming minerals (Quartz, Feldspar, Mica, Calcite, Hematite, Galena). Briefly introduce the concept of rock-forming minerals and their importance in mining and geology in Nigeria. State the lesson objectives clearly. Key Concept Explanation - Naming Minerals (20 minutes): Define "mineral" and "rock-forming mineral." Present the major rock-forming minerals, emphasizing their common names and basic characteristics (e.g., color, luster, common rock type found in). Use a chart or projector to show images. Highlight some minerals significant to Nigeria (e.g., Quartz, Feldspar, Calcite, Hematite, Cassiterite, Galena, Barite). Key Concept Explanation - Classification by Crystal Form (25 minutes): Introduce the concept of crystal systems. Explain each of the seven crystal systems (Isometric, Tetragonal, Orthorhombic, Hexagonal, Trigonal, Monoclinic, Triclinic) using visual aids (3D crystal models if available, or clear diagrams showing axes and angles). Provide one or two common mineral examples for each system (e.g., Halite for Isometric, Quartz for Trigonal, Orthoclase for Monoclinic). Emphasize that the internal atomic arrangement dictates the external crystal form. Key Concept Explanation - Classification by Chemistry (30 minutes): Introduce the chemical classification of minerals based on their anionic groups. Systematically explain each major chemical class: Native Elements, Sulfides, Oxides, Halides, Carbonates, Sulfates, Phosphates. For each class, provide the general chemical characteristic and 2-3 common mineral examples, linking to Nigerian occurrences where possible (e.g., Cassiterite for Oxides, Calcite for Carbonates). Elaborate on the Silicate class, explaining the fundamental SiO4 tetrahedron. Then, introduce and briefly explain the subdivisions (Nesosilicates, Sorosilicates, Cyclosilicates, Inosilicates, Phyllosilicates, Tectosilicates) with key examples for each.
Facilitation & Guidance: Circulate among students during activities, answering questions and providing assistance. Ensure safety protocols are followed if handling actual mineral samples. Encourage critical thinking and discussion. Review key concepts through questioning and summarizing. 3.
2. Student Activities: Observation and Description (15 minutes): Students observe actual mineral samples (if available) or pictures provided by the teacher. In groups, students attempt to describe the basic features of each mineral (e.g., color, luster, estimated hardness, presence of crystal faces). Students record their observations in their notebooks.
Group Discussion & Naming (15 minutes): Based on teacher's input and their observations, groups discuss and attempt to name the rock-forming minerals presented. They compare their observations with provided reference charts or information.
Crystal System Matching (20 minutes): Using diagrams or models of different crystal forms, students work in pairs to match common rock-forming minerals to their respective crystal systems. They can sketch simple representations of the crystal systems in their notebooks. Chemical Classification Exercise (20 minutes): Students are given a list of common rock-forming minerals and their chemical formulas (e.g., Quartz - SiO2, Calcite - CaCO3, Galena - PbS, Gypsum - CaSO4·2H2O). In groups, they classify each mineral into its correct chemical group (Sulfide, Oxide, Silicate, Carbonate, Sulfate, etc.) and justify their choices based on the chemical formula.
Note-taking and Q&A: Students actively take notes throughout the lesson. They ask clarifying questions during explanations and activities.
Understanding the physical and chemical properties of rock-forming minerals has numerous practical applications in Nigeria: Mineral Exploration and Mining Industry: Ore Identification: Mining engineers and geologists utilize mineral properties to identify economically valuable ore minerals (e.g., identifying cassiterite (SnO2) for tin, galena (PbS) for lead, hematite (Fe2O3) for iron) and distinguish them from gangue (waste) minerals. This is crucial for guiding exploration efforts in areas like the Jos Plateau (tin), Benue Trough (lead-zinc), and Itakpe (iron ore).
Processing and Beneficiation: The chemical and physical properties dictate how minerals will respond to crushing, grinding, flotation, and chemical leaching. For example, the perfect cleavage of micas can make them problematic in some aggregates, while the specific gravity of cassiterite allows for gravity separation. Construction and Infrastructure Development: Aggregates: Sand, gravel, and crushed stone used in concrete, roads, and building materials are composed of rock-forming minerals like quartz and feldspar. Their hardness, durability, and resistance to weathering (physical properties) are critical for the longevity of infrastructure projects across Nigeria. For instance, granite and gneiss (composed of these minerals) are widely quarried for construction in states like Ogun, Oyo, and Ebonyi.
Cement Production: Limestone (predominantly calcite, CaCO3) is a primary raw material for cement production in Nigeria (e.g., Ewekoro, Nkalagu). Understanding its chemical composition and reactivity with heat is fundamental to the cement industry. Gypsum (CaSO4·2H2O) is also added to cement as a setting retarder.
Agriculture and Soil Science: Soil Fertility: The mineralogy of soils significantly influences their fertility and physical properties. Clay minerals (a subgroup of phyllosilicates like kaolinite and montmorillonite), abundant in many Nigerian soils, determine water retention capacity, nutrient exchange, and soil workability. Understanding their chemical structure helps in formulating appropriate agricultural practices and fertilizers. For example, highly weathered lateritic soils, common in tropical Nigeria, derive their properties from specific iron and aluminum oxide/hydroxide minerals.