Re: What exactly is a rock?

A rock is a combination of two or more minerals. Minerals are defined as "The building blocks of rocks." They are naturally occurring substances which are combinations of chemicals that are found in nature. There are three kinds of rocks; Sedimentary, Igneous, and Metimorphic.

Sedimentary rocks are made up from bits and pieces of other rocks that wear away and are packed together underwater over millions of years into new rocks. This is the ONLY kind of rock where fossils are found.

Igneous rocks come from red hot, liquid rock that escapes from inside of the earth. Volcanic rocks are igneous. They come in two main types; Intrusive (ones that cool and harden INside the earth) and Extrusive (ones that cool and harden on the surface of the earth).

Metamorphic rocks come from deep inside the earth. They are new rocks that are made when other, older rocks deep underground are put under great heat and pressure (usually caused by earthquake or volcanic activity). This warps and molds the old "parent" rocks into a new, different rock.

You can find a great site about rocks (although it is from Britain) at the following address:
http://www.bbc.co.uk/education/rocks/

It has some fun ideas for rock studies that you can do at home. Another great website that actually looks at rocks in your home state is: http://www.pittstate.edu/services/scied/Teachers/Stupage/Chambers/chambers.htm

This one has pictures of rocks that are found around your home state, and tells about the experiences of a group of student teachers who went on a field trip to see them.

I hope this information helps to answer your questions