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"ROCK IDENTIFICATION
KEY"
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| 1. (a) If the rock is grainy or is
made up of more than one material, go to 2. (a). If it
is not, go to 1. (b). (b) If the rock is made up of only one king of material, go to 5. (a). 2. (a) If the rock is made up of particles or grains that are closely fitted together like tiny pieces in a jigsaw puzzle (interlocking), go to 3. (a). If it is not, go to 3. b). (b) If the rock is made up of particles or grains that are held in place by natural cement (non-interlocking), go to 6. (a). Otherwise, go to 6. (b). 3. (a) If all the grains are of the same type, the rock is METAMORPHIC. (b) If the grains in the sample are of two or more different types, go to 4. (a). 4. (a) If the grains in the sample are not lined up but are distributed randomly, the rock is IGNEOUS. If they are not, go to 4. (b). (b) If the grains in the sample are not distributed randomly but seem to line up, forming bands, the rock is METAMORPHIC. 5. (a) If the rock is either glassy or frothy (having small holes), it is IGNEOUS. If not, go to 5. (b). (b) If the rock is made up of strong, flat sheets that look as though they will split off, it is METAMORPHIC. 6. (a) If the rock is made of silt, sand, or pebbles cemented together (it may have fossils), it is SEDIMENTARY. (b) If the rock is not made of silt, sand, or pebbles but contains a substances that fizzes when dilute hydrochloric acid is poured on it, it is SEDIMENTARY.
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