Aim: How can igneous rocks differ from one another? Do Now: Regents worksheet Homework: Igneous Rocks classification WS

How does the size of the crystals depend on cooling?

How do these two igneous rocks differ? Texture - Crystal size depends on the rate of cooling and where the rock cooled –Beneath the surface (Intrusive) – magma cools slowly – makes large crystals –Above the surface (extrusive) – lava cools quickly – makes small to no-visible crystals

How does the texture of these two intrusive igneous rocks differ? Coarse-grained Magma cools slowly (deep underground) Crystals have a lot of time to grow Visible interlocking crystals Ex. Granite or Gabbro Intrusive rocks textures: Very-coarse grained Magma - extremely long time to cool Extremely large visible crystals Ex. Pegmatite

How does the texture of these two extrusive igneous rocks differ? Fine-grained Fast cooling lava (above the ground) Crystals grow fast in less time Small crystals- hard to see on rock – need a magnifying glass Ex. Basalt or Rhyolite Extrusive rocks textures: Vesicular Holes or vesicles left by gas bubbles that escaped as the lava cooled quickly (solidified) Ex. Scoria or Pumice

How would you describe the texture of the extrusive igneous rock Morgan Freeman finds? Glassy texture: (non-crystalline) Extrusive (Volcanic) Lava cools quickly & rapidly Crystals have no time to grow Ex. Obsidian Obsidian appears black BUT is felsic and has conchoidal fracture

small big small big Describe the relationship between Crystal size and Time! Time Crystal size less more Rate of cooling Crystal size Slow Fast Describe the relationship between Crystal size and Rate of cooling! As Time increases Crystal size increases As Rate of cooling increases Crystal size decreases

Summary - Igneous Texture Activity In your notes, determine the texture of each igneous rock and explain why you chose that texture. Glassy Texture Vesicular Texture Fine Texture Coarse Texture

Extra Summary Questions

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Summary - Igneous Texture Activity In your notes, determine the texture of each igneous rock and explain why you chose that texture. Glassy Texture Vesicular Texture Fine Texture Coarse Texture Very Coarse Texture