How rocks change into another?

Question

Let me know if any of these ar wrong and what the right answer would be!! Especially number 6. Thanks

Rocks change from different causes.


1. Metamorphic to igneous- Rock is changes with heat and low pressure to form a new rock by melting.
2. Metamorphic to sedimentary- Rock goes from high silica content to low silica content.
3. Sedimentary to igneous- Rock melts, then cools to form another rock.
4. Sedimentary to metamorphic- Rock is broken into pieces and cements to another rock later on.
5. Igenous to metamorphic- Rock is changed under heat and high pressure without melting
6. Igneous to sedimentary- Rock melts and cools then forms another rock?

Answer 1

Is this a true or false school work assignment?

1. F - it would usually take high Pressure
2. F - silica content has nothing to do with erosion
3. T - yes, that is how igneous melts are derived
4. T or F - normally metamorphism results from increased P and T, but there is also dynamic metamorphism, such as blue schist
5. T
6. F - sedimentary rocks are usually formed by erosion, not melting

Hopefully you're not cheating on a school work assignment.

Answer 2

Igneous rocks are formed from molten material. You can melt any type of rock, and when the magma cools it will be considered Igneous. The key is melting and then cooling, not necessarily pressure (which is important for metamorphic rocks). Sedimentary rocks are formed when other rocks are eroded by wind/water and the particles are transported, deposited and then, later, cemented together. Igneous and metamorphic rocks can create sedimentary rocks in this manner, and sedimentary rocks can be eroded again to create a different sedimentary rocks. 2: metamorphic to sedimentary has nothing to do with silica content 4: would be correct for metamorphic to sedimentary, but it's wrong for sedimentary to metamorphic (see below) Take any rock, subject it to varying amounts of heat and pressure (the heat isn't enough to melt the rock) and you'll have a metamorphic rock. So, for 4, you start with a sedimentary rock, squeeze and/or heat it and you'll have a metamorphic rock. I hope that helps..

Answer 3

It is due to changes in the structural atomic arrangement, polymorphic changes. Sometimes the process induces change that result in modifications on the chemical composition, which leads to new structures.

A chemical compound will show an atomic arrangement depending on the conditions of temperature and pressure. For example graphite and diamond are both carbon, under different atomic arrangements; they show quite different properties.

Another example, If you take volcanic lava and cool it abruptly in water, the result will be an amorphous material, which is reactive towards alkaline solutions. On the other hand, if you allow the lava to cool very slowly, it will form crystalline compounds that could be very stable in various chemical environments.

Hope it helped, it is not a simple subject