<p> Ch 20 and 21 notes</p><p>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:</p><p>1) Igneous – Formed from or hardened or .</p><p>2) Sedimentary – Formed from or deposits of .</p><p>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:</p><p>1) Extrusive </p><p> Cools on Earth’s </p><p> Because of cooling, crystal sizes are very .</p><p>2) Intrusive</p><p> Cools while trapped Earth’s </p><p> Slow cooling aids in crystal development. Examples of Igneous Rock:</p><p> </p><p> Examples of Igneous Rock:</p><p> SEDIMENTARY ROCK Characteristics of sedimentary rock: 1) Named according to the of rock they contain.</p><p>2) Think of sedimentary rock as “ ” rock. It is made from the of older rock and sometimes remains of living , called .</p><p>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”.</p><p> Formed from rocks that undergo and/or without melting</p><p> Formed from either , or rock</p><p>Examples:</p><p> Limestone to (sedimentary to )</p><p> ______to gneiss ( to metamorphic)</p><p> Shale to ( to metamorphic) THE ROCK CYCLE ______Rocks form Rocks AGE DETERMINATION OF ROCKS ______Age can be determined looking at rock :</p><p> Assuming no change in the position of the rock layers, the will be on the , and the will be on the .</p><p> Radioactive can determine the age of rocks.</p><p> Radioactive dating gives the age of the rock.</p>