Regents Lab Practical Review Mrs Regents Lab Practical Review Mrs. Cohn Rocks (any words in white can be used to distinguish rocks from each other as an observable characteristic)

ROCKS ARE FURTHER CLASSIFIED ACCORDING TO TEXTURE Can you (1)identify a rock type (2) based upon observable characteristics? The 3 rock types (according to how they were formed): Sedimentary Rock (most are made from compaction and cementation of sediments or organic matter) Igneous Rock (made from the cooling and solidification of magma (inside) or lava (outside earth) Metamorphic Rock (recrystalization made from subjecting heat and/or pressure at depths within the earth of pre-existing rock ROCKS ARE FURTHER CLASSIFIED ACCORDING TO TEXTURE

Common textural traits identified in sedimentary rock “Clastic” – means it has visible sediments present (whether sand, silt, clay or pebbles) “Bioclastic”- means it has visible organic matter present (shells if limestone or compacted plant remains if coal-black and crumbly!) Other distinguishing features that tell you the rock is sedimentary: It has layers (of sediments NOT alternating light and dark minerals..), or fossils

1. What is the classification of this rock and what observable characteristic is evidence?

2. What is the classification of this rock and what observable characteristic is evidence? Let’s Zoom In ! ! !

3. What is the classification of this rock and what observable characteristic is evidence?

4. What is the classification of this rock and what observable characteristic is evidence?

Igneous rock textures Most Igneous rocks have visible crystals. Since igneous rocks are formed by the solidification of magma/lava, many crystals form in the process. Crystals in igneous rocks cool and form a random pattern (like splotches of paint) vs. foliation found in some metamorphic rocks.

Other textures If the rock forms extrusively (outside/lava), the lava cools too fast producing a non-crystalline. So how do these rocks look different than say a shale? Vesicular/Has Gas Pockets; like scoria, basalt or pumice Glassy; like obsidian

5. What is the classification of this rock and what observable characteristic is evidence? Let’s Zoom In ! ! !

6. What is the classification of this rock and what observable characteristic is evidence?

7. What is the classification of this rock and what observable characteristic is evidence?

8. What is the classification of this rock and what observable characteristic is evidence?

9. What is the classification of this rock and what observable characteristic is evidence?

Metamorphic Rocks Many metamorphic rocks have visible crystals just as igneous rocks do, however, there are a few ways to tell them apart. These two textures form when metamorphic rocks are subjected to high pressures. Foliation or Mineral Allignment: ex: minerals of micas (biotite/muscovite) appear to align in platy like sheets. Banding: found in Gneiss, where there are alternating light (felsic) and dark (mafic) layers of minerals. This is what separates layers in sedimentary rock vs. metamorphic rock Distortion: When banding in gneiss appears folded

Foliation to compare in slate, schist and gneiss

10. What is the classification of this rock and what observable characteristic is evidence?

11. What is the classification of this rock and what observable characteristic is evidence?

What processes from the rock cycle changed rock “A” into “B” What processes from the rock cycle changed rock “A” into “B”? What class is rock “A” and “B”? B A

Answers Rocks 1-4 are all sedimentary rocks. 1- layers present, 2-clastic/made of pebbles and other sediments, 3-fossils present, 4- bioclastic/made of shells Rocks 5-9 are all igneous rocks 5-vesicular, 6- intergrown coarse crystals, 7-intergrown crystals, 8- glassy, 9- intergrown crystals Rocks 10-11 are metamorphic 10- banding, 11- foliation of mica or mineral allignment of mica