In what way do magnetic minerals align with the earth's magnetic field?
Magnetic minerals align parallel to the earth's magnetic field.
Lets look a little further into how magnetic minerals are classified, and why it is important to know how they align within earth's magnetic field.
In order for a mineral to be magnetic it must contain certain elements. Minerals not containing these elements are what are known as diamagnetic, meaning they have no magnetism.
Other minerals, specifically ones containing the elements Ti, Cr, V, Mn, Fe, Co, Ni, and Cu, are able to interact with magnetic fields, including the earth's, however only very weakly. Interestingly, once these minerals are removed from a strong magnetic field, they lose all magnetism, and cannot function as magnets themselves. These are known as paramagnetic minerals.
Other minerals, known as ferromagnetic minerals, are permanently magnetic, as long as they are in an environment below a specific temperature, defined as the Curie temperate. These minerals will become magnetized when placed in a strong magnetic field, and remain that way once removed. The most notable example of this type of mineral is Magnetite.
Analysis of the alignment of these types of magnetic minerals, trapped in stone as it formed and hardened from liquid magma, has provided scientists with evidence that earth's magnetic field actually shifts the location of its poles over time. During this shift, what we know today, as magnetic north actually becomes located in the south, and vice versa, meaning a compass that points north today, would point south when the poles are flipped!
Hope this helps!