Metamorphic Rocks Section 4-3
Dec 28, 2015
Metamorphic Rocks
Section 4-3
Metamorphic Rocks
Rocks that have changed due to heat and pressure
Banding effect – causes the minerals to become squashed in lined or banded (foliated) forming a gneiss.
2 ways gneiss is formed
Flattening due to pressure from above
Stretching due to pulling along fault lines
Flattened rock with foliation versus stretched rock with
lineation. Illustration by Anne Crowder.
Foliation
Notice banding of mineralsNotice bending of bands due to
folding pressure
Causes of heat and pressure
Heat – 1. Radioactive decay 2. Contact with magma
pools
Pressure 1. Overlying rock 2. Plate boundaries
Formation of Metamorphic rocks
Classification of Metamorphic Rocks
Foliated Rocks – minerals are flattened and line up in parallel bands
Ex. Gneiss – forms from granite
Slate – forms from shale
- minerals so tightly packed water cannot pass through
Careful on this pronunciation. There’s an “s” before the “t”.
Schist – layering of minerals
Ex. Mica schist
Metamorphic rocks that are not banded. (nonfoliated)
Nonfoliated rocks – no banding occurs
- mineral grains change, grow and rearrange
Ex sandstone (mostly quartz) – forms quartzite.
Marble – formed from limestone
Marble
Calcite – give it a shiny appearance
Hornblende and serpentine – give it its greenish tint
Hematite – give it is reddish tint
Used in statues
Textbook page 102answer in notebook
Self check – 2,3,4 Applying skills