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Difficulty: MediumRock Types, Formation, and Economic Importance

Below is a list of specific rock specimens alongside various geological formation mechanisms and economic applications. Match each rock specimen to its corresponding origin process and primary practical utilization.

  • RhyoliteExtrusive felsic volcanic rock with fine-grained texture; utilized as decorative stone and road aggregate.
  • ChertMicrocrystalline siliceous sedimentary rock formed by chemical precipitation or organic accumulation; used for abrasives and cutting tools.
  • AmphiboliteRegional metamorphic rock dominated by hornblende amphibole; derived from mafic igneous precursors and used for crushed heavy construction aggregate.
  • DolomiteCarbonate sedimentary rock formed via magnesium replacement of calcium in pre-existing limestone; used as a metallurgical flux in steelmaking.

Answer

Rhyolite matches the extrusive felsic volcanic rock utilized as decorative stone; Chert matches the microcrystalline siliceous sedimentary rock used for abrasives; Amphibolite matches the regional metamorphic rock derived from mafic precursors; Dolomite matches the magnesium-replaced carbonate sedimentary rock used as a metallurgical flux.
Each rock specimen is accurately paired based on its primary genetic category (igneous, sedimentary, metamorphic), mineral composition, and commercial utilization in industrial and construction settings.

Step-by-Step Solution

1
Identify the genetic classification and composition of Rhyolite
Rhyolite is the extrusive equivalent of granite, characterized by rapid lava cooling and high silica content.
Extrusive volcanic cooling produces fine-grained textures distinguishing rhyolite from intrusive granite.
2
Determine the formation environment of Chert
Chert consists of microcrystalline quartz deposited from siliceous skeletal remains or inorganic silica precipitates.
Siliceous chemical sedimentary rocks differ fundamentally from clastic mudstones and organic limestones.
3
Analyze the protolith and metamorphic grade of Amphibolite
Amphibolite forms via regional metamorphic alteration of mafic igneous rocks under elevated temperatures and pressures.
Hornblende mineral dominance reflects high-grade alteration of basaltic parent material.
4
Evaluate the diagenetic alteration involved in forming Dolomite
Dolomite forms when magnesium ions replace calcium ions in existing limestone, creating a magnesium-rich carbonate.
Magnesium substitution alters chemical properties, making dolomite suitable for high-temperature refractory applications.

Key Concept

Rock Types, Formation Processes, and Economic Importance
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Topics

Rock Types, Formation, and Economic Importance

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