Ch 20 and 21 notes

All are composed (made of) . So, what are minerals? A mineral is a , (non-living) solid with a definite chemical ______and a characteristic internal . There are 3 types of rocks Three types of rocks:

1) Igneous – Formed from or hardened or .

2) Sedimentary – Formed from or deposits of .

3) Metamorphic – Formed when either , , or rock is exposed to heat, pressure, or processes. IGNEOUS ROCKS When rocks form, they are formed from either very cooling of the and lava or very cooling. The that magma/lava determines size of the rock. There are two types of igneous rocks:

1) Extrusive

 Cools on Earth’s

 Because of cooling, crystal sizes are very .

2) Intrusive

 Cools while trapped Earth’s

 Slow cooling aids in crystal development. Examples of Igneous Rock:



 Examples of Igneous Rock:

 SEDIMENTARY ROCK Characteristics of sedimentary rock: 1) Named according to the of rock they contain.

2) Think of sedimentary rock as “ ” rock. It is made from the of older rock and sometimes remains of living , called .

There are ways sediment can become rock: 1) Conglomerate - dissolved in water seep between bits of rock and other material and “ ” them together 2) As sediment , the layers on the bottom get from the weight of sediment above, forming rock. METAMORPHIC ROCKS The term comes from the Greek word metamorphosis which means “to form”.

 Formed from rocks that undergo and/or without melting

 Formed from either , or rock

Examples:

 Limestone to (sedimentary to )

 ______to gneiss ( to metamorphic)

 Shale to ( to metamorphic) THE ROCK CYCLE ______Rocks form Rocks AGE DETERMINATION OF ROCKS ______Age can be determined looking at rock :

 Assuming no change in the position of the rock layers, the will be on the , and the will be on the .

 Radioactive can determine the age of rocks.

 Radioactive dating gives the age of the rock.