Factors affecting density change:
* Mineral Composition: Metamorphism can cause new minerals to form within the rock. These new minerals may be denser or less dense than the original minerals.
* Recrystallization: Metamorphism can cause existing minerals to recrystallize, resulting in larger, more tightly packed crystals, increasing density.
* Pressure: The high pressure of metamorphism can force atoms closer together, increasing density.
* Dehydration: Metamorphism can drive off water and other volatiles, increasing density.
Examples:
* Shale to Slate: Shale is a relatively low-density sedimentary rock. Metamorphism of shale into slate results in a denser rock with a more compact structure.
* Limestone to Marble: Limestone is a relatively low-density sedimentary rock. Metamorphism of limestone into marble often leads to a denser rock due to the recrystallization of calcite minerals.
* Granite to Gneiss: Granite is a relatively dense igneous rock. Metamorphism of granite into gneiss can result in a slightly less dense rock due to the formation of minerals like mica that are less dense than the original quartz and feldspar.
Conclusion:
The change in density during metamorphism is a complex process that depends on several factors. It's not a simple "always more dense" or "always less dense" situation.
