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Question

Difficulty: MediumRock Types, Formation, and Economic Importance

Match each rock type in Column I with its correct parent rock or mode of formation in Column II.

  • MarbleThermal or regional metamorphism of limestone
  • SlateLow-grade metamorphism of clay or shale
  • QuartziteMetamorphic recrystallization of quartz sandstone
  • CoalCompaction and carbonization of organic plant remains

Answer

Marble corresponds to the metamorphism of limestone; Slate corresponds to the metamorphism of clay or shale; Quartzite corresponds to the recrystallization of quartz sandstone; Coal corresponds to the compaction of organic plant remains.
Each rock is matched strictly according to its geological formation process: Marble is metamorphosed limestone, Slate is metamorphosed clay or shale, Quartzite is metamorphosed sandstone, and Coal is formed organically from buried plant matter.

Step-by-Step Solution

1
Determine the origin of Marble
Marble is formed when limestone undergoes metamorphic transformation.
Calcium carbonate grains in limestone recrystallize under heat and pressure into interlocking calcite crystals.
2
Determine the origin of Slate
Slate is derived from shale or clay under low-grade metamorphic conditions.
Directional pressure aligns microscopic clay minerals perpendicular to stress, creating characteristic slaty cleavage.
3
Determine the origin of Quartzite
Quartzite forms from quartz sandstone during metamorphism.
Extreme pressure and heat fuse individual silica sand grains into a continuous crystalline matrix.
4
Determine the origin of Coal
Coal originates from accumulated organic vegetable matter.
Anaerobic decay and continuous burial convert plant debris into peat, lignite, and bituminous coal.

Key Concept

Metamorphic parent rocks (protoliths) and organic sedimentary rock formation
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Topics

Rock Types, Formation, and Economic Importance

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