Rock cycle science project

[Einstein2000]

Hi, I am doing a school project on the rock cycle. I hope this is the right forum to post this in! Im trying to make a demonstration of how metamorphic rocks are made. I have some shiny glittery brown powder (this is suppose to represent the dirt). My dad made me a presser using a box, a lid and c-clamps. I moisten the brown powder a bit, then put the brown powder into the presser and put the lid on top then use the c-clamps the apply pressure. After half an hour I take it out and it is a rock, which is good. When I break open the rock though to test how hard it is, its always kind of chalky on the inside. All of the shine and glitter is gone. But when I look at metamorphic rocks in real life and online, the shine and glitter is usually there on the inside like in this picture:

 

http://www.google.ca/imgres?imgurl=http://geology.com/rocks/pictures/muscovite-schist.jpg&imgrefurl=http://geology.com/rocks/metamorphic-rocks.shtml&h=420&w=560&sz=61&tbnid=nZo1-c_J7BCKuM:&tbnh=95&tbnw=126&zoom=1&usg=__5NNdDEllPM6IGe9MmV9MYKf_tdk=&docid=TtO9MYTwnJjqiM&sa=X&ei=j9IyUuC7CsXQ2QWjioDoBQ&ved=0CEEQ9QEwAw&dur=315

 

 

What is making the shine go away when I put the shiny powder into the presser? How can I make it stay so that my rock cycle demonstration is more accurate?

 

 

[studiot]

Hello einstein (I've always wanted to say that),

 

Your apparatus does not demonstrate metamorphic rocks I'm afraid.

 

It sounds like it does a good job of demonstrating sedimentary rocks however.

 

Metamorphic rocks are subject to extreme temperature and or pressure. The temperature may be as a result of the pressure or it may be as a result of contact with very hot molten rock coming up from the interior, with little or no pressure involved.

 

Either way the temperature is enough to cause (partial) melting and recrystallisation of the material to form the metamorphic rock. This is usually involve chemical change.

 

Sedimentary rocks, on the other hand are simple compressed material laid down under the pressure of stuff above. It may be that some sort of binding material comes out of solution as lakes or seas evaporate and cements the otherwise non sticky particles together.

 

There are all sorts of iffs and buts, but this is the basic outline.

[Einstein2000]

Oops! I guess i will have to change my project to sedimentary rocks then. I am curious though, how come all the shiny and glittery stuff in my brown powder went away when i put it in the presser? On the surface of the rock its still shiny, but not in the middle. I tried before to put less pressure on it and it seems that the less pressure i put, the more the glittery stuff stays, but then its too soft. Im just curious because i have been trying for over s week to correct that problem!

[studiot]

You will have to ask your dad what the glittery brown stuff is. I would guess that as you compress the powder the shiny grains rub together and rub/grind off some fine powder that coats the grains making them dull.

 

I don't know what your science experiment does all together, but an interesting variation might be to consider what happens with some hard beads that do not squash down.

If you look carefully there are large spaces between the beads that you cannot fill unless you have some particles (grains) of different (smaller) sizes to go into the gaps.

Between these smaller particles there will be again smaller gaps that need even smaller particle to fill and so on.

 

This process is called grading in earth science. It also appears in materials technology like concrete and in chemistry in crystal structures, so is worth looking into if you are interested.

 

go well with your project.