Earth's Water, Minerals, and Rock Formations

The Hydrosphere: Oceans, Seas, and Freshwater

The hydrosphere comprises the Earth's water. Oceans and seas account for 97% of this water, while freshwater makes up the remaining 3%.

Freshwater Distribution

Freshwater is distributed as follows: 78% in glaciers, 21% in subterranean sources, and 1% on the surface.

Key Properties of Water

Water possesses several unique properties:

• It is a good solvent.
• It absorbs large amounts of heat.
• Its thermal expansion (dilatation) is abnormal.
• It is adherent.

Ocean Water Movements

Ocean water exhibits three primary movements:

• Waves: Caused by wind.
• Currents: Movement of large water masses.
• Tides: The periodic rise and fall of sea levels.

The Water Cycle

The water cycle is the continuous set of steps and processes that water undergoes. Key stages include:

• Condensation
• Precipitation
• Infiltration
• Runoff

Water Treatment and Distribution

The typical stages of water treatment and distribution are:

• Capturing and preliminary treatment (roughing).
• Pre-treatment and ozonation.
• Decantation and filtration.
• Chlorination and dechlorination.
• Pumping and distribution.

Sources of Water Contamination

Water can be contaminated by:

• Discharges from industries and farms.
• Urban wastewater.
• Oil spills.
• Pesticides and fertilizers.

Understanding Minerals

Minerals are solids formed by the chemical combination of elements within the Earth's crust. Rocks, in turn, are composed of minerals.

Characteristics of Minerals

Minerals typically possess the following characteristics:

• They are naturally occurring.
• They have an inorganic origin.
• They possess a homogeneous chemical composition (meaning they are a single substance).

Minerals are considered pure substances, with a composition involving a single type of substance. However, if different impurities are present (often affecting color), the mineral is said to have varieties.

Mineral Structures

Minerals can exhibit different structural arrangements:

• Amorphous: Components are disordered.
• Crystallized: Components are ordered, forming a crystalline structure.

Types of Minerals: Silicates

Silicates are minerals that contain both silicon and oxygen. Examples include quartz, mica, and clay minerals.

Types of Minerals: Non-Silicates

Non-silicate minerals do not contain silicon. Examples include blende, cinnabar, galena, calcite, and fluorite.

Mineral Formation Conditions

Mineral formation requires components in sufficient quantities and at the proper temperature. This can occur within molten rock at high pressures and temperatures, or through crystallization processes.

Mineral Properties

Key properties used to identify minerals include:

• Color
• Luster (brightness)
• Hardness
• Streak (color stripe)
• Cleavage (exfoliation)

Importance and Uses of Minerals

Minerals are vital for:

• Obtaining metals.
• Ceramics industries.
• Development of new materials.
• Jewelry.

Mineral Extraction Methods

Minerals are typically obtained through mining, including opencast (surface) mines or underground mines.

Exploring Rock Types and the Rock Cycle

Sedimentary Rocks

Sedimentary rocks are formed by the accumulation and compaction of sediments. They usually exhibit a layered arrangement, known as strata. Common types include detrital, limestone, evaporites, and organic rocks (formed by accumulation and sedimentation). Examples of materials associated with sedimentary rocks include gypsum, rock salt, coal, and oil.

Igneous Rocks

Igneous rocks are formed by the cooling and solidification of magma.

Metamorphic Rocks

Metamorphic rocks are formed deep within the Earth's crust due to high pressures and temperatures.

Igneous Rock Formation (Magmatism)

Igneous rocks are formed through magmatism, which occurs when magma (a mixture of gases and molten rock) solidifies. These can be classified as:

• Plutonic (Intrusive): Formed deep underground.
• Volcanic (Extrusive): Formed on or near the surface (e.g., basalt or pumice).

Metamorphic Rock Formation

Metamorphic rocks are formed through metamorphism, which is the set of changes experienced by a rock when subjected to high pressures and temperatures. Examples include slate, schist, marble, and quartzite.

The Rock Cycle

The rock cycle describes the continuous set of processes experienced by rocks and sediments both on the Earth's surface and within its crust.

Uses of Rocks

Rocks are utilized for various purposes, including:

• Construction materials.
• Ornamental purposes.
• Containers.
• Fuel (e.g., coal).
• Chemical industry.