The igneous rocks
The first rock I will be talking about is obsidian. Obsidian looks like a dark black glass rock. It forums by lava, and it can forum by water and lava. Obsidian is a igneous rock. It is where lava closes fast.
Another igneous rock is Granite. Granite is forums by slow criticizing lava under earth surface. The color of it can be red, pink, gray etc. Granite is made up of quartz, feldspar etc.
The last igneous rock I am talking about will be Tuff. Tuff is made by exploding volcanos. Tuff is the thickest around volcanos. Tuff is sometimes 100 meters thick. The website I got this from is http://geology.com/rocks/
Marble is a metamorphic rock. It is forms with limestone and heat and pressure. That is what makes marble. Marble has minerals in it like clay and graphite etc.
Amphibolite is a metamorphic rock. It forms by heat and pressure. The color of it is green black and brown. The Amphibolite is a member of the hornblende group.
The last rock I will be talking about is Soapstone. It is formed by heat and pressure. The use of soapstone is for counter tops, bed wormers, woodstoves, and etc. The web site I used for this is http://geology.com/rocks/.
The next rock i am talking about is iron ore. How iron ore was made was when the first organism capsule was letting oxygen in the water. Iron is used for steel, ships, and beams, etc.
The last rock I will be talking about is Chert. How Chert is made is when microcrystals of silicon grow with dioxide sedimentary that will become chalk or limestone. Where I got all of this info I give credit to http://geology.com/rocks/sedimentary-rocks.shtml