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Our transcription: Different geologists use minerals in different ways. A "geochronologist" uses minerals to determine the age of a rock, whether it be in millions or billions of years. He uses the radioactive elements that are in each mineral. The "sedimentary petrologist" and "stratigrapher" use minerals in a sediment to determine how that sediment was formed into a sedimentary rock. Some of those minerals in the sediment tell that geologist about mountains that were once there eroded to deformed sedimentary rock. The "igneous petrologist "and the "metamorphic petrologist" used minerals to determine the pressure and temperature recorded during a rock's crystallization from a molten magma or deformation during metamorphism. In plate tectonics, a "structural geologist "uses minerals as well. Many minerals record magnetic directions, and as the plates have migrated, the magnetic directions are shifted, and so minerals have recorded plate motion. So, we have learned about where the plates once were relative to today from the minerals. Different geologists have learned different things, but the minerals have recorded that information despite their great antiquity of age.
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