Rocks Notes

  1. Igneous Rocks
  2. IGN – fire
  3. ignite – to start a fire
  4. Igneous rocks start out as magma or lava
  5. Magma – melted rock BENEATH the earth’s surface
  6. Lava – melted rock ON the earth’s surface (ie – volcano erupting)
  7. When the magma/lava cools, it becomes an igneous rock
  8. There are two types of igneous rock
  9. Extrusive – forms ON the earth’s surface, cools and hardens in AIR or WATER
  10. Cools very FAST, so there is not a lot of time for crystals to grow. These rocks have either SMALL crystals or NO crystals.
  11. Examples are Pumice, Scoria, Obsidian, and Basalt
  12. Intrusive – form IN the earth’s crust, beneath the surface, and are NOT exposed to air or water while they harden.
  13. Cools very SLOWLY, so there is a lot of time for crystals to grow. These rocks have visible crystals.
  14. Examples include Granite.
  15. Uses of igneous rocks include:
  16. Basalt – crushed for gravel
  17. Granite – used for tile, countertop, and decoration
  18. Pumice – used for health/beauty and for cleaning products
  19. Sedimentary Rocks
  20. Formed from sediment – loose pieces of minerals or rock
  21. Layers of sediment build up and put pressure on the layers below, cementing them together
  22. Many sedimentary rocks may contain fossils of plants or animals
  23. There are three types of sedimentary rock
  24. Organic
  25. forms when the remains of plants and animals are deposited in thick layers – COAL
  26. Clastic
  27. forms when rock fragments are squeezed together and cemented – SANDSTONE, CONGLOMERATE
  28. Chemical
  29. forms when water that contained minerals evaporates. The water evaporates, the minerals stay behind and crystallize – LIMESTONE, HALITE (rock salt)
  30. Uses of sedimentary rock include:
  31. Sandstone and limestone – building materials
  32. White House in Washington, DC is made of sandstone
  33. Limestone is ground up to make concrete for buildings, roads, and sidewalks.
  34. Metamorphic Rocks
  35. Key words – HEAT and PRESSURE
  36. Rock is softened to a plastic like consistency
  37. The minerals in the rock may change, or rearrange
  38. ANY ROCK can become a metamorphic rock if exposed to high HEAT and extreme PRESSURE.
  39. There are two types of metamorphic rock
  40. Foliated – which means banded or striped – GNEISS, SLATE, SCHIST
  41. Non-Foliated – which means no banding or stripes – QUARTZITE, MARBLE
  42. Uses of metamorphic rock include:
  43. Marble is used for building materials and statues
  44. Slate is used for roofing, paving, and chalk boards