Earth Science 1st Semester (STEM)

Minerals are naturally-occurring inorganic substances with a definite and predictable chemical composition and physical properties.

  1. Color - The wavelength of light reflected from the mineral’s surface, is not always an effective property for identifying minerals. Sulfur is always yellow so its color is always a distinguishing property.


  2. Luster - the way light is reflected from the surface of the mineral. It is the way a mineral shines or doesn’t shine. Minerals can have metallic or non-metallic luster.

    Metallic - shiny, from igneous rocks, malleable

    Non-metallic - don’t have a shiny appearance, from sedimentary rocks, non-malleable


  3. Hardness - a mineral’s ability to resist abrasion or scratching.

    -The Mohs Hardness Scale is used as a convenient way to help identify minerals. A mineral's hardness is a measure of its relative resistance to scratching, measured by scratching the mineral against another substance of known hardness on the Mohs Hardness Scale.


  4. Streak - color of the mineral in powder form. It is tested by rubbing a metallic mineral across a piece of unglazed porcelain called a streak plate.

    Streak plate - a piece of unglazed porcelain used in testing the streak of a rock


  5. Crystal Shape - the outward expression of a mineral’s orderly internal arrangement of atoms. The cubic shape of halite (salt) crystals results from the regular arrangement of sodium and chlorine atoms forming the crystal.

Fracture - the way a mineral breaks when it doesn’t break along cleavage planes

Cleavage - when a mineral breaks into flat surfaces along planes of weak bonding in the crystal structure

Specific Gravity - the weight of a mineral compared to the weight of an equal volume of water

Native Elements - minerals composed of only one element

  • Example: Sulfur (S), Diamond (C), Graphite (C), Gold(Au), Silver (Ag), Copper (Cu) Platinum (Pt)

Types of Rocks

A. Igneous Rocks

  • Formation: Cooling and solidification of magma/lava

  • Types:

    1. Intrusive (Plutonic)

      • Formed inside the Earth

      • Slow cooling

      • Examples: Granite, Diorite

    2. Extrusive (Volcanic)

      • Formed on the Earth's surface

      • Rapid cooling

      • Examples: Basalt, Pumice

B. Sedimentary Rocks

  • Formation: Compaction and cementation of sediments

  • Types:

    1. Clastic

      • Formed from fragments of other rocks

      • Examples: Sandstone, Shale

    2. Chemical

      • Formed from precipitation of minerals

      • Examples: Limestone, Rock Salt

    3. Organic

      • Formed from the remains of living organisms

      • Examples: Coal, Chalk

C. Metamorphic Rocks

  • Formation: Transformation of existing rocks under heat and pressure

  • Types:

    1. Foliated

      • Layered appearance

      • Examples: Schist, Gneiss

    2. Non-foliated

      • No distinct layers

      • Examples: Marble, Quartzite

Key Vocabulary for Types of Rocks

1. Igneous Rocks

  • Magma: Molten rock beneath the Earth's surface.

  • Lava: Magma that reaches the Earth's surface.

  • Intrusive (Plutonic): Igneous rocks formed from magma that cools slowly underground (e.g., granite).

  • Extrusive (Volcanic): Igneous rocks formed from lava that cools quickly on the surface (e.g., basalt).

  • Crystals: Solid materials whose atoms are arranged in a highly ordered structure.

  • Texture: The size, shape, and arrangement of crystals in a rock.

2. Sedimentary Rocks

  • Sediments: Particles of minerals, rocks, or organic materials that accumulate over time.

  • Lithification: The process of turning sediments into rock through compaction and cementation.

  • Strata: Layers of sedimentary rock.

  • Fossils: Preserved remains or traces of ancient organisms found in sedimentary rocks.

  • Clastic: Sedimentary rocks formed from fragments of other rocks (e.g., sandstone).

  • Chemical: Sedimentary rocks formed from the precipitation of minerals from solution (e.g., limestone).

  • Organic: Sedimentary rocks formed from the accumulation of plant or animal debris (e.g., coal).

3. Metamorphic Rocks

  • Metamorphism: The process by which existing rocks are transformed by heat, pressure, and chemically active fluids.

  • Parent Rock (Protolith): The original rock from which a metamorphic rock forms.

  • Foliation: The alignment of mineral grains in a rock, giving it a layered appearance (e.g., schist).

  • Non-foliated: Metamorphic rocks that do not have a layered appearance (e.g., marble).

  • Regional Metamorphism: Metamorphism that occurs over large areas under high pressure and temperature.

  • Contact Metamorphism: Metamorphism that occurs when rocks are heated by nearby molten magma.

Examples of Igneous Rocks and Their Uses

I. Introduction to Igneous Rocks

  • Definition: Formed from the solidification of molten material (magma or lava).

  • Types: Intrusive (plutonic) and Extrusive (volcanic).

II. Examples of Intrusive Igneous Rocks

  1. Granite

    • Composition: Quartz, feldspar, mica.

    • Uses:

      • Construction (buildings, monuments).

      • Countertops and flooring.

  2. Diorite

    • Composition: Plagioclase feldspar, biotite, hornblende.

    • Uses:

      • Decorative stone.

      • Road base material.

  3. Gabbro

    • Composition: Pyroxene, plagioclase, olivine.

    • Uses:

      • Crushed stone for construction.

      • Dimension stone for buildings.

III. Examples of Extrusive Igneous Rocks

  1. Basalt

    • Composition: Pyroxene, plagioclase, olivine.

    • Uses:

      • Road construction (asphalt).

      • Aggregate in concrete.

  2. Pumice

    • Composition: Volcanic glass with gas bubbles.

    • Uses:

      • Abrasives (pumice stones).

      • Lightweight aggregate in concrete.

  3. Obsidian

    • Composition: Volcanic glass.

    • Uses:

      • Cutting tools (sharp edges).

      • Jewelry and decorative items.

IV. Special Types of Igneous Rocks

  1. Rhyolite

    • Composition: High silica content, similar to granite.

    • Uses:

      • Landscaping stone.

      • Source of pumice.

  2. Andesite

    • Composition: Intermediate between basalt and rhyolite.

    • Uses:

      • Construction material.

      • Decorative stone.

Crushed stone is used for foundations, road base, concrete, and drainage.

Sand and gravel are used in concrete and foundations.

Clays are used to make cement, bricks, and tile. Iron ore is used to make reinforcing rods, steel beams, nails, and wire.

Gypsum is used to make drywall. Dimension stone is used for facing, curbing, flooring, stair treads, and other architectural work.

Mind Map: Rock Cycle

Central Idea

  • Rock Cycle

Main Branches

1. Types of Rocks

  • Igneous Rocks

    • Formed from molten magma

    • Examples: Granite, Basalt

  • Sedimentary Rocks

    • Formed from sediment compression

    • Examples: Sandstone, Limestone

  • Metamorphic Rocks

    • Formed from existing rocks under heat and pressure

    • Examples: Schist, Marble

2. Processes

  • Cooling/Crystallization

    - Solidification of magma into igneous rock

    - Can happen underground or on the surface

  • Weathering

    • wears rocks at the Earth’s surface down into smaller pieces

    • Breakdown of rocks by wind, water, and ice

    • the small fragments are called sediments.

    • Types: Mechanical, Chemical

  • Erosion

    • Movement of sediments from one location to another

    • Agents: Water, Wind, Ice

  • Sedimentation

    • Accumulation of sediments in layers

    • Occurs in bodies of water, deserts, etc.

  • Lithification

    (Compaction, cementation)

  • Metamorphism

    When a rock is exposed to extreme heat and pressure within the Earth but does not melt, the rock becomes metamorphosed. Metamorphism may change the mineral composition and the texture of the rock. For that reason, a metamorphic rock may have a new mineral composition and/or texture.

  • Melting

    • Process where rocks turn into magma

    • Occurs in subduction zones and hot spots


Types of Rocks

Igneous Rocks

  • defined as a type of rock that is formed through the cooling & solidification of lava or magma

MAGMA - It is a molten rock generated by partial melting of rocks in Earth’s mantle and in the lower crust in smaller amounts. This molten material consists mainly of the elements found in silicate minerals.

Two Types of Igneous Rock

  1. Extrusive or Volcanic - Igneous rocks that form when molten rock solidifies at the surface.

    Example: Rhyolite, Andesite, Bassalt, Obsidian

  2. Intrusive or Plutonic - Igneous rocks that form at depth. Exposures of intrusive igneous rocks occur in many places, including Mount Washington, New Hampshire; Stone Mountain, Georgia; Mount Rushmore in the Black Hills of South Dakota; and Yosemite National Park, California.

    Example: Granite, Diorite, Gabbro, Peridotite


Mount Rushmore National Memorial, located in the Black Hills of South Dakota, is carved from the intrusive igneous rock granite. This massive igneous body cooled very slowly at depth and has since been uplifted and the overlying rocks stripped away by erosion.

Crystallization - as magma cools, random movements slow, and atoms begin to arrange themselves into orderly patterns.

The rate of cooling strongly influences crystal size.

  • slow cooling results in the formation of large crystals.

  • rapid cooling results in the formation of a solid mass of small intergrown crystals.


Igneous rocks are composed mainly of silicate minerals. Chemical analysis shows that silicon and oxygen—usually expressed as the silica (SiO2) content of a magma—are by far the most abundant(SiO2) constituents of igneous rocks.

2 Major groups of silicate minerals

  1. Dark silicates - are rich in iron and/or magnesium and are relatively low in silica.

    Examples: Olivine, pyroxene, amphibole, and biotite mica


  2. Light silicates - contain greater amounts of potassium, sodium, and calcium and are richer in silica than dark silicates.

    Examples: quartz, muscovite mica, and feldspars

Classification of Igneous Rocks

  1. Texture - describes the overall appearance of an igneous rock, based on the size and arrangement of its interlocking crystals.


    Kinds of Texture

    1. Fine-grained texture - produced when lava cooled quickly on or near Earth’s surface. The individual crystals are too small to be seen with the unaided eye.

      Example: Rhyolite, Andesite, Bassalt

    2. Vesicular Texture - These are voids, called vesicles, left by gas bubbles that formed as the lava solidified.

      Example: Pumice, Scoria

    3. Coarse-grained texture - Produced when magma cools slowly at depth. Roughly equal in size and large enough that individual minerals can be identified with the unaided eye.

      Example: Granite, Diorite, Gabbro

    4. Porphyritic texture - It results when magma that already contains some large crystals migrates to a new location where the rate of cooling increases.

    5. Glassy Texture - Produced by very rapid cooling that no crystals have time to form.

      Example: Obsidian - a dark volcanic glass that can be polished and used as a mirror

    6. PYROCLASTIC TEXTURE - A rock with a pyroclastic texture is termed a tuff if the largest fragments are less than 2.5 inches long, a volcanic breccia if the fragments are larger.

    7. Frothy Texture - rapid cooling of gas-rich lava

      Example: Pumice - forms when large amounts of gas escape from molten rock to generate a gray, frothy mass.



  2. Mineral Composition - Is largely a consequence of the chemical makeup of the parent magma and the environment of crystallization.


    a. Granitic (Felsic) Rocks- are rocks composed almost entirely of light-colored silicates(quartz, potassium feldspar) and 10% of dark silicate minerals(biotite mica and amphibole)

    Examples: granite, rhyolite

    b. Basaltic (Mafic) Rocks - Rocks that contain substantial dark silicate minerals and calcium-rich plagioclase feldspar (but no quartz).

    Examples: basalt, gabbro

    c. Andesitic (Intermediate) Rocks - Rocks with a composition between granitic and basaltic rocks

    Examples: andesite, diorite

    d. Ultramafic rocks - Contains mostly the dark-colored minerals olivine and

    pyroxene .

    Example: peridotite, komatite



Sedimentary Rock

  • Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth's surface. Sedimentary rocks often have distinctive layering or bedding.

    Example: Breccia, Sandstone, Shale


Metamorphic Rock

  • A metamorphic rock is a result of a transformation of a pre-existing rock. The original rock is subjected to very high heat and pressure, which cause obvious physical and/or chemical changes.

    Example: Amphibole, Quartz, Gneiss