Based on the analysis of each rock sample and its geological classification, here is the correct placement for each rock type into the categories of Igneous, Sedimentary, or Metamorphic:
IGNEOUS
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Granite: An intrusive igneous rock formed from the slow cooling of magma.
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Obsidian: An extrusive igneous rock, a volcanic glass formed by rapid cooling.
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Pumice: An extrusive igneous rock, a vesicular volcanic rock formed from frothy lava.
SEDIMENTARY
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Limestone: A chemical or biochemical sedimentary rock formed from the accumulation of marine organisms.
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Sandstone: A clastic sedimentary rock composed of sand-sized grains.
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Conglomerate: A clastic sedimentary rock composed of rounded gravel-sized clasts.
METAMORPHIC
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Quartzite: A metamorphic rock formed from the metamorphism of sandstone.
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Slate: A low-grade metamorphic rock formed from the metamorphism of shale or mudstone.
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Marble: A metamorphic rock formed from the metamorphism of limestone or dolomite.
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Shale: Although often listed as sedimentary, in this context, it is likely intended to be placed with slate. However, shale is technically a fine-grained *sedimentary* rock. Given the list, "shale" might be an error, or it could be referring to its metamorphic equivalent, which is slate. For accuracy, shale belongs in Sedimentary, but if forced to choose based on common classroom groupings with slate, it might be misclassified here. The most accurate placement for shale is Sedimentary.
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Gneiss: A high-grade metamorphic rock with a banded or foliated appearance.
Therefore, the final classification is:
IGNEOUS: Granite, Obsidian, Pumice
SEDIMENTARY: Limestone, Sandstone, Conglomerate, Shale (Note: Shale is sedimentary)
METAMORPHIC: Quartzite, Slate, Marble, Gneiss
Parent Tip: Review the logic above to help your child master the concept of rock types worksheet.
