Which one of the following is not an igneous rock ?

Igneous rocks are formed through the solidification of magma or lava [5]. Granite and gabbro are classified as intrusive (plutonic) igneous rocks that cool slowly beneath the Earth's surface, resulting in large crystals [3]. Basalt is an extrusive (volcanic) igneous rock formed from the rapid cooling of lava on the surface [3]. In contrast, dolomite is not an igneous rock; it is a carbonate mineral and a common rock-forming mineral often associated with sedimentary processes. Sedimentary rocks, unlike igneous rocks, are formed from the accumulation and consolidation of sediments or organic matter on the Earth's surface [2]. Therefore, while granite, gabbro, and basalt are all primary igneous rocks, dolomite belongs to a different geological classification.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 13: Types of Rocks & Rock Cycle > 13.1. Igneous Rocks or Primary rocks > p. 169
2. [5] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 3: Interior of the Earth > Intrusive Forms > p. 24
3. [3] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 2: The Earth's Crust > Chapter 2 The Earth's Crust > p. 18
4. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 13: Types of Rocks & Rock Cycle > Some Examples of Metamorphosis > p. 174