4a. Draw the rock cycle. State two characteristics of the three (3) main rock types
b. State three (3) characteristics of a mineral.
c. State the composition and three (3) properties of the core.
a. The rock cycle can be represented as follows:
Igneous rocks form when molten rock (magma or lava) cools and solidifies. They can be further classified as intrusive (formed beneath the Earth's surface) or extrusive (formed on or above the Earth's surface). Two characteristics of igneous rocks are their crystalline structure and their formation from the cooling of molten rock.
Sedimentary rocks are formed from the accumulation and compaction of sediments, such as sand, mud, or organic material. They can also be formed through the precipitation of minerals from water. Two characteristics of sedimentary rocks are their layering or stratification and their ability to contain fossils.
Metamorphic rocks are formed when pre-existing rocks are subjected to high pressure, temperature, or chemical changes without fully melting. This transforms the original rock into a new type of rock with different mineral composition and texture. Two characteristics of metamorphic rocks are their foliated (layered or banded) or non-foliated (no visible layering) texture and the presence of minerals arranged in a specific alignment.
b. Three characteristics of a mineral include:
1. Definite chemical composition: Each mineral has a specific chemical formula, representing the elements and their proportions that constitute it. For example, quartz is composed of silicon and oxygen (SiO2).
2. Naturally occurring: Minerals are formed through natural geological processes and are not artificially created.
3. Crystalline structure: Minerals have an ordered arrangement of atoms, resulting in a specific crystal lattice structure. This lattice structure determines the mineral's physical properties, such as its hardness, cleavage, and shape.
c. The Earth's core is composed of two layers: the outer core and the inner core.
Outer Core:
- Composition: The outer core is primarily composed of liquid iron (Fe) and nickel (Ni).
- Properties: The outer core is responsible for generating Earth's magnetic field due to the movements of the molten metal. It is also very hot, with temperatures reaching up to 5,000 degrees Celsius.
Inner Core:
- Composition: The inner core is composed mainly of solid iron (Fe) and nickel (Ni).
- Properties: The inner core is under extreme pressure, causing the solid iron and nickel to maintain a solid state despite the high temperature. It is the Earth's hottest layer, with temperatures estimated to reach even higher than the outer core, up to 6,000 degrees Celsius.