Understanding Rock Classification

Rocks are broadly classified into three major types based on their formation process:

• Igneous Rocks: Formed from the cooling and solidification of molten rock (magma or lava).
• Sedimentary Rocks: Formed from the accumulation, compaction, and cementation of sediments (fragments of other rocks, minerals, or organic matter).
• Metamorphic Rocks: Formed when existing rocks (igneous, sedimentary, or other metamorphic rocks) are transformed by heat, pressure, or chemical reactions.

The question asks us to identify the rock types from the given list that are not metamorphic rocks. Let's classify each rock type provided:

• Schist: This is a metamorphic rock, typically formed from fine-grained sedimentary rocks like shale or mudstone, or igneous rocks like basalt.
• Slate: This is also a metamorphic rock, formed from the low-grade metamorphism of shale or mudstone.
• Basalt: This is an igneous rock, specifically an extrusive volcanic rock formed from rapidly cooling lava.
• Marble: This is a metamorphic rock, formed from the metamorphism of limestone or dolostone.
• Gneiss: This is a high-grade metamorphic rock, often formed from granite, sedimentary rocks, or volcanic rocks.
• Quartzite: This is a metamorphic rock, formed from the metamorphism of sandstone.
• Limestone: This is a sedimentary rock, composed primarily of calcium carbonate, often from the accumulation of marine organisms' shells.

Based on this classification, the rocks from the list that do not fall under the category of Metamorphic rocks are Basalt and Limestone.

Basalt is an igneous rock, and Limestone is a sedimentary rock. All other rocks in the list (Schist, Slate, Marble, Gneiss, Quartzite) are metamorphic rocks.

Therefore, the pair of rock types that do not fall under the category of Metamorphic rocks is Basalt and Limestone.