Objective: 1.Describe processes of rock formation. 2. Compare and contrast intrusive and extrusive igneous rocks. 3. Classify different types and textures of igneous rocks 4. Recognize the effects of cooling rates on the grain sizes of igneous rock 5. Describe some uses of igneous rocks

Rocks: Mineral Mixtures (Elements) S6E5b & c. S6E5b: Investigate the composition of rocks in terms of minerals & S6E5c: Classify rocks by their process of formation.

aturally occurring olid norganic ixed composition rystalline structure What is a mineral? olid aturally occurring norganic SNIFC ixed composition rystalline structure

What is a ROCK Exactly? SNI olid aturally Occurring s made up of minerals or organic matter. SNI

ROCK A naturally occurring solid mixture of one or more minerals or organic matter.

Texture Is the size (course), shape (tiny like seeds), pattern (multicolored), and positions of the grains that make up the rock. A rocks texture is the look of the rock’s surface, determined by the size, shape, pattern, and position of the grains. (How it looks)

Grains gives the rock texture. Grains-particles (pieces) of minerals or other rocks. Grains gives the rock texture. Siltstone Sandstone Conglomerate Fine-grained Medium-grained Coarse-grained

COMPOSITION The chemical makeup of a rock; describes either the minerals or other materials in the rock. The combination of elements or compounds (minerals the rock is made up of) that make up a rock.

Rocks are composed of (made up of) two or more minerals. What’s the difference? Minerals have a Definite chemical composition and a characteristic crystalline structure. May be a single element such as copper (Cu) or gold (Au), or it May be a compound made up of a number of elements. Rocks are composed of (made up of) two or more minerals.

Compare Contrast mineral in terms of a rock Difference Fixed composition Difference How are they ALIKE Naturally occurring Solid Organic matter

Classification System Classified according to its color, texture and mineral composition. Using these characteristics a geologist can determine the rock’s origin or where and how it formed.

Origins of Igneous Rocks where they are formed ex- means “out of” or “outside.” In- means “within or into”; Extrusive Rocks: These rocks are formed above the ground when lava flows or explodes from a volcano. Intrusive or plutonic igneous rock Rock: These rocks form underground from magma. Granite Basalt Obsidian Gabbro

Texture of Igneous Rocks Texture depends on the size and shape of the crystals when the rock forms. This is due to the cooling rate of the rocks. Slow Cooling: Slow cooling produces coarse grains with large crystals. This is associated with intrusive rocks. Rapid Cooling: Rapid cooling produces fine grains and small crystals. This is associated with extrusive rocks. Diorite Andesite

Let’s pull it all together! Small OR invisible grains Large grains