Question

Analyze the following statements about the origin and naming of rocks:

1. Igneous rocks are derived from the Latin word for fire.
2. Primary rocks are those that result from the solidification of molten material.
3. Pegmatite is a sedimentary rock.

• A. All
• B. 1, 2
• C. 1, 3
• D. None of these

Answer 1

Answer:

B. 1, 2

Origin and Naming of Rocks

Igneous Rocks

• The term Igneous is derived from the Latin word 'ignis', which means 'fire'. This name accurately reflects their origin from the cooling and solidification of molten rock (magma or lava).
• Igneous rocks are often referred to as primary rocks or parent rocks because they are the original rocks from which other rock types (sedimentary and metamorphic) are formed through various geological processes.
• These rocks are classified based on their composition and texture, which are influenced by the cooling rate and chemical makeup of the magma/lava.
• Examples include Granite, Basalt, Obsidian, and Pumice.

Sedimentary Rocks

• Sedimentary rocks are formed from the accumulation and cementation of mineral and organic particles on the Earth's surface.
• Pegmatite is NOT a sedimentary rock. It is a type of igneous rock, specifically an intrusive igneous rock characterized by extremely large crystal sizes. These large crystals form due to slow cooling of a silica-rich magma with a high water content.
• Examples of sedimentary rocks include Sandstone, Shale, Limestone, and Conglomerate.

Metamorphic Rocks

• Metamorphic rocks are formed when existing rocks (igneous, sedimentary, or even other metamorphic rocks) are transformed by heat, pressure, or chemical reactions, without melting.
• Examples include Marble (from limestone), Slate (from shale), and Gneiss (from granite or other rocks).