Rocks

I. Rocks are aggregates (mixtures) of minerals or simply large samples of one mineral.

1. Usually, rocks are ______(have more than one mineral), such as granite.

2. Rocks are NOT identified using the tests you used for mineral identification.

3. The minerals in rock help determine the name of the rock.

4. The ______of the rock determines which TYPE of rock it is.

II. There are 3 main categories (types) or rocks:

  1. ______(‘fire’ rock) Links to Animations
  2. ______(rock from particles of other rocks, etc)\\Vc_hs\vol1\Users\HS\students\JMCMAHON\grand canyon.htm
  3. ______(rocks that have ‘changed form’)

III. Igneous rocks igneous pix

  1. Igneous rocks are called ‘fire rocks’ because they form from ______or ______.
  2. Magma is called ______because that is where the elements come together that will form minerals as magma cools.
  3. Igneous rocks are called the ______of all others.
  4. All igneous rocks have ______, because they form as the magma cools, and each crystal grows into the ones around them. Some crystals are so small that we can’t see this without the use of a ______.
  5. Igneous rocks are classified (see page 6 of ESRT) according to:
  6. the ______of the rock, which is determined by the magma or lava that forms the rock. As old rock pushes down into the mantle and melts, it mixes with magma that is already there, forming slightly different magma. Over time, different igneous rocks have formed. Minerals have different colors, and these colors help identify the type of igneous rock.
  7. the ______or grain size of the rock, which is determined by how quickly or slowly the magma cools to form rock.

c. Together, mineral composition and texture identify the rock.

  1. In the ______, the melting points for common igneous minerals are shown. Minerals with high melting points form crystals ______, while those with low (cool) melting points (typical of crust closer to the surface) forms crystals ______.
  2. When the magma cools deep below the ground, it is called ______or plutonic, and the minerals formed will be ______grained.

When the magma cools NEAR the surface, much more ______, the crystals don’t have much time to form and the rock is called ______or volcanic, and the minerals will be ______grained. Glassy minerals form ______.

8. The three main igneous families, ______, ______and basaltic are described in the lab and lecture and text. The families are identified according to the type of ______from which they form, which are characterized by the minerals and color.

  1. The GRANITE family, formed from ______magma, makes up the CONTINENTAL CRUST, which is low density (______) compared with the ocean crust (______).
  2. The ______family, formed from ______magma, makes up the ocean crust. Its density explains why ______
  3. The third family is the ______family, which comes from magma that is a mixture of both mafic and felsic minerals, therefore its minerals have characteristics of both granites and basalts.
  1. Porphyritic textures refer to igneous rocks that have VARIOUS sized minerals, like a chocolate chip cookie. This happens when the magma ______in stages.
  2. In summation, Igneous rocks are identified in the lab by comparing their:

______, which tells you what minerals are in it, and therefore what magma it came from and the ______, which indicates whether the rock cooled quickly or slowly (extrusive or intrusive).

IV. Sedimentary rocks

  1. Form from ‘pieces’ or ______of other rocks, or from chemical or biological processes. Identified by ______, lithification (how they formed) and composition.
  2. While igneous rocks reach down many miles beneath the crust, sedimentary rocks form a thin ______on the top of earth’s ______, because these rocks form (mostly) when pre-existing rock is ______by exposure to weather and the pieces are dumped in one place and pile up over time.
  3. Rocks that form from weathered pieces of other rocks are called ______rocks. Clastic rocks (see page 7 of ESRT) are named according to the ______of the particles/sediments from which they are made. Small particles are often ______together, while it takes ______to hold larger particles together in the ______, breccias and some sandstones.
  4. Most sedimentary rocks form in ______because rivers carry the sediments and then drop them as they slow down when entering an ocean or lake. The particles drop according to ______, and in layers. This layering is called ______.
  5. Clastic sedimentary rocks may have particles that are from MANY different types of other rocks and the particles may be of many different AGES. The youngest part of any sedimentary rock is the ______that holds it together, but the rock is ______than any particle in it.
  6. Non-clastic sedimentary rocks come from two processes:
  7. ______or biological (coal and shell limestone)
  8. Chemical (precipitates and ______)
  9. ______, such as chemical limestone, occur when ions come together and fall to the bottom as a new substance.
  10. Evaporites, such as halite and gypsum, form when shallow seas ______, leaving the minerals behind.
  11. Fossils are usually ONLY found in sedimentary rock, commonly in shales, siltstones and limestones. Only the gentle layering of sediments can preserve the imprint of a fossil. Igneous rocks come from ______, which ruins the imprint, as does the partial melting that occurs when ______rocks form.

V. Metamorphic Rocks

  1. These form when pre-existing rocks are ______due to heat and pressure.

(If the old rock melts, then it does not become metamorphic, because melted rock produces magma and igneous rock).

  1. Metamorphic rocks are ______versions of pre-existing rock. The minerals often just line up differently. Intense metamorphism will really change the minerals, too.
  2. Metamorphic rock are classified according to:
  3. The presence or type of ______, which is seen by observing the texture of the rock. This must be observed in lab and using pictures.
  4. The second identifier is the composition of the rock, especially when discussing the non-foliated rocks. For example, marble and quartzite look a lot alike, but are made of very different minerals. (the ______test identifies marble and a comparison of ______shows which is quartzite).
  5. Rocks formed by intense pressure generally have the minerals align at a perpendicular to the direction of the pressure. This often forms the ______texture.
  6. The type of foliation is described on page ______of the ______.
  7. Rocks formed by intense heat are often called ______rocks because they are usually bands of rock that are ______due to the presence of nearby lava or magma flows, which partially ______the rock.
  8. Contact metamorphic rock are found along igneous ______as the magma heats the rock. Zones of metamorphic rock usually are found between igneous rocks and other rocks.
  9. Identifying metamorphic rocks is pretty tricky, and requires patience (and sometimes a good stereomicroscope)