Crystals form in many shapes, sizes, and colors.
Crystals are usually formed at depths beneath the Earth's crust where conditions such as temperature and pressure are favorable for their formation. The process of formation of crystals is known as crystallization, and are formed from an aggregation of different crystals. Crystallization can occur naturally at certain depths below the Earth's crust or can be carried out artificially through various scientific experiments in a laboratory. Magnetism in crystals is usually achieved when such crystals form within a magnetic field in the Earth's crust. A crystallization process forms solid crystals that precipitate from a solution or from gaseous deposits.
The Crystallization Process
Any crystallization process is made up of two major phases; nucleation and crystal growth. In the nucleation process solute molecules are dispersed in a solvent (liquid phase) and start to gather into clusters. Stable clusters are formed under favorable natural conditions. The crystal growth process is the subsequent growth of these stable clusters to form crystals of different sizes. The main driving force of any crystallization process is super-saturation. Magnetism may occur in crystals formed in a magnetic field of the Earth's crust. Remanent magnetism is magnetism in rocks and can be acquired at the time crystals within the matrix of a crystalline rock form, retaining specific magnetic properties. Magnetism in crystals formed under natural conditions is termed "natural remanent magnetism."
Natural Remanent Magnetism
There are two major types of natural remanent magnetism: primary and secondary natural remanent magnetism. Natural remanent magnetism is a record of the Earth's magnetic field as it existed when a certain rock formed. Magnetic crystals in igneous rocks have specific magnetic properties. Geomagnetic fields and other geological processes at the time of formation play an important role in the magnetization of crystalline rocks.
Thermoremanent Magnetism
As the name implies, thermoremanent magnetism is a form of primary natural remanent magnetism that occurs mainly due to temperature conditions present at the time a rock formed. In , thermoremanent magnetism is produced when rock crystals cool above the Curie temperature in the presence of a magnetic field. A small magnetic field at elevated temperatures can thus impact on ferromagnetic crystal grains as they cool to produce a remanent magnetism or remanence. This remanence over time becomes stable and, as such, crystals of a rock can be resistant to certain magnetic fields.
Chemical Remanent Magnetism
This occurs as a result of chemical changes that form crystals of ferromagnetic rocks at a certain temperature in a magnetizing field. Chemical reactions involving ferromagnetic rocks, which can in turn produce crystals that possess magnetic properties, including alteration of preexisting minerals to form a ferromagnetic mineral and precipitation of ferromagnetic minerals from a solution.
Viscous Remanent Magnetism
This is a secondary remanent magnetism, which is gradually acquired when crystalline rocks are exposed to weak magnetic fields. This usually results from the action of a geomagnetic field long after such crystalline rocks have been formed, producing a weak magnetism in crystals of such a rock. Chemical may displace original magnetism of the crystals of an igneous rock after original formation.
Tags: crystalline rocks, magnetic field, Earth crust, crystallization process, , remanent magnetism